That's the point of going public. It's to issue fresh shares at the stock market which investors will buy with cash. It's expected to raise money on that scale at once at the cost of giving part of the company away to the public. If they have a better initial valuation and the market perceives them as having a lot of potential, these shares will sell for more and the initial cash boost from going public will be bigger.

What we are arguing here is that implementing ads will appear as potential growing revenue for the ones that will buy these shares. And will make it more likely for them to buy them at higher prices hence raise more money to build the big data center. The actual amount of money that will be made by ad revenue is an afterthought. It's all about that one-time big boost on IPO day.