Companies IPO'd at an earlier stage of development in the days before Sarbanes-Oxley. Netscape was a 16-month-old startup when it IPO'd. It had about 250 employees. It had raised a total $27M in venture capital then, and then raised a few hundred million in the IPO itself, which gave it a total valuation of $2.9B. It had $16M in revenue and no earnings.

OpenAI is 10 years old. It has about 4500 employees. It's raised about $180B in capital, and has a valuation of roughly $900B on about $25B in revenue. Anthropic is 5 years old. It also has around 3000-5000 employees. It will have raised about $120-140B in capital, at a $900B valuation, on about $30-45B in revenue.

In the 80s and 90s companies IPO'd to actually raise growth capital - the public markets provided the money they needed to invest and expand, and then public investors reaped the benefits of their success, or paid the price of their failure. In the 2010s and 2020s companies grow with private capital, which has fewer strings attached, and then they unload the shares on the public market when they reach the top of their growth curve, leaving the public holding the bag.