https://www.economist.com/finance-and-economics/2018/09/29/american-startups-have-less-need-to-list-on-the-stockmarket
"He has drawn fresh attention to some familiar grumbles about public markets. The number of listed firms in America is in long-term decline (see chart). Mr Musk’s beefs seem specific, but they are part of a general explanation for this trend. The red tape, the endless disclosures, the ceaseless spotlight—all have made the cost of being a public company too high. Yet that is not the real cause. The main reason why startups do not become public firms is that many of them no longer need to."
Firms can now privately raise hundreds of millions of dollars privately. Also, since most new startups are digital in nature, they just don't require as much backing. Software can be copied at almost zero cost.
Do you still see a place for IPO's?
Now if you do not go public than you would need to sell your shares to someone directly which means they gain control and you need to try to find a fair price for it instead of letting the market decide on your price. All these considered going public is still in the best interest of the company owners.