Ballantyne said she was also older now.
"And it's a much different industry with all the regulations. To start up something like that you need massive money now."
Ballantyne wouldn't say exactly how much she had made from building up and selling down the business.
"I will be very comfortable. But certainly not on New Zealand's richest list and that is just fine by me.
"I'm very happy that the risk I took to start the business and put everything we owned into it has paid off. We will be very comfortable for the rest of our lives and that is all I need. I'm just really happy for all of our shareholders."
Partners' Life share registry shows the largest shareholder currently is US private equity firm Blackstone Group through its subsidiary Immortality Pte, followed by Partners Group Nominee company with 21 per cent.
New Zealand's Maui Capital Aqua fund is the third largest shareholder with 9.3 per cent. Rangatira, Stahl Capital, Masfen Securities, Kibo Investments and Waterman also have minority stakes.
The Ballantyne Investment Trustee company exited the business in April 2016.
Ballantyne has talked about listing Partners Life through an initial public offer for years.
"We had always talked about a listing and listing is a liquidity event. You know that one of the opportunities that comes out of a listing is the potential flushing of a trade buyer.
"But listing seemed like such a long way away. So when [Dai-ichi] approached us first at the very end of last year with an expression of interest and then a non-binding offer in April...we went into full-on due diligence."
But she said global uncertainty in the markets meant it was both exciting and terrifying right up until the deal was signed on Friday.
"Until you have a signed deal, it could fall over and the world is turning to custard and you don't know what pressures are on people's capital. To get a signed deal was an enormous relief."
Ballantyne is staying on as CEO of Partners Life for now and says her main job is to put its BNZ life transaction to bed.
It acquired BNZ's life insurance business at the end of 2020 for $290m but is still waiting to get approval from the Reserve Bank.
The sale to Dai-ichi Life also requires RBNZ approval and sign-off from the Overseas Investment Office.
"Then really it will be pushing my team around me to fill up the space. When I think that is done, the Dai-ichi Life world is enormous. I think they see in me as an entrepreneurial culture driver and innovator."
Partners Life has more than 260 staff and is the second largest life insurer in New Zealand. Accounts show it made an underlying insurance profit of $23.6m in the year to March 31, 2022, down from $30.77m in the prior financial year.
It had net assets of $673.3m up from $593.3m.
Ballantyne might help the Japanese company with developing other markets. Dai-ichi already owns life insurance businesses in eight other countries.
"For as long as I want to remain and I can contribute, the world is my oyster with them really, which is exciting as well."
