The sale of my business for $3.7 billion left me feeling regretful on my 'saddest day'.

The Moment series by CNBC Make It features successful individuals discussing the pivotal moment that altered their career paths and lives.

Jyoti Bansal realized a dream that many can only imagine: He founded his own business, received an irresistible acquisition offer, and sold it for a fortune.

Today, it's among his biggest regrets.

In 2017, Bansal, 46, founded software developer AppDynamics, which was set to go public. However, at the last minute, tech giant Cisco bought the company for $3.7 billion. The deal made hundreds of employees, including Bansal, instantly wealthy. Despite the joy of becoming wealthy, Bansal considers it his "saddest day," he tells CNBC Make It.

Bansal, who was born in India and had long dreamed of becoming an entrepreneur, worked as a Silicon Valley software engineer for eight years until he received a Green Card. After launching his own startup, he built AppDynamics to address the biggest problems he faced as an engineer, creating tools for troubleshooting outages and other software application flaws.

""At the beginning of [AppDynamics], my focus was solely on solving the problem at hand, rather than considering the financial implications," he states."

After selling AppDynamics to Cisco, Bansal realized that he hadn't fully accomplished his mission at the company, which could have grown even more significantly, and he felt aimless without a major issue to tackle.

Bansal, after six months of global travel, founded a San Francisco-based startup called Harness, which creates software development tools. The company's valuation was $3.7 billion in 2022, the same as AppDynamics' sale price.

Bansal talks about his decision to sell AppDynamics, his immediate regrets and why he would likely reject a similar offer for his startup now.

January 2017: You sold AppDynamics for $3.7 billion. How do you feel in that moment of triumph?

We hosted a joyous celebration at our San Francisco office after announcing the sale, and many people from Cisco attended.

After walking home, I felt sad and depressed. For nine years, I had devoted myself entirely to the project we were working on. Now, it seems like the end of a chapter.

Selling your company can be a bittersweet experience, as it represents a significant accomplishment but also marks the conclusion of a chapter or book. I felt lost after the sale.

What was your initial reaction to Cisco's last-minute offer?

We were about to go public, and we weren't stopping our IPO. The AppDynamics board had six days to figure out how we were going to proceed.

Although others may believe it was the simplest choice, it was actually the most challenging decision I had to make. For three consecutive nights, I managed only three hours of sleep. We spent days discussing and weighing different options before making a final decision.

As the chairman of the board and the largest shareholder, I was responsible for leading many of those discussions.

What were the biggest factors you considered?

Is it possible to complete the task within the given timeframe? Is it the right decision to proceed with the acquisition? What is the shared history of the two products and the two companies? Does the acquisition align with our initial vision?

We could be part of a larger platform, such as Cisco, and their customer base and market. The second factor is culture, specifically the kind of work environment our employees experience. Cisco, to their credit, did an excellent job of providing a high degree of independence to the AppDynamics unit.

Is it the right thing for the stockholders, including founders, investors, and employees, financially? As the only founder, I was fortunate enough that any outcome financially would be fine for me. However, we had about 300 or so employees who made more than a million dollars in the final offer we accepted. We had dozens of employees with $5 million-plus outcomes.

That's life-changing, so it all became risk versus reward.

Although you appeared to have made the best choice on paper, why are you still feeling down or uncertain?

If someone said, "Your company could be worth $100 million," I would have thought it was an incredible achievement.

I enjoyed building the company, creating products, solving problems, competing in the market, every element of company building that I'd gone through. Although it was intense and stressful, I really enjoyed it. I also felt like we didn't fully finish what we could've done.

I wanted to explore the world, but everyone advised me to retire and relax on the beach.

In six months, I completed my bucket list. However, I came to the realization that there was more to life than just accomplishing my goals.

If you received a great last-minute offer to sell Harness, what would you do regarding a potential IPO?

We must consider the proposal, but I suspect the outcome will probably be negative.

At Harness, we aim to achieve billions of dollars in revenue by expanding into new markets, products, and solving more problems. We prioritize creating an organizational culture that fosters this growth. As long as we can maintain this focus, I am committed to this goal.

Our journey is just beginning, so it doesn't make sense to sell to someone else. We have so much room to grow from here.

So, the answer is no — unless something crazy happens.

This interview has been edited and condensed for clarity.

Sign up for CNBC's online course to master your money this fall. Our practical strategies will help you hack your budget, reduce your debt, and grow your wealth. Start today to feel more confident and successful. Use code EARLYBIRD for a 30% introductory discount, extended through September 30, 2024, for the back-to-school season.