Top tier firms are actually the ones most guilty of it these days. They raise huge funds (thanks to Softbank) and attempt to buy their way into monopoly positions by selling dollars for 50 cents, manufacturing growth and then dumping the companies on the public market (these days through SPACs). Public markets are no different than private, it's the same group of individuals just further down the chain, with the same incentives to push up valuations knowing that stonks can only go up and when things go bad we'll be on the hook to rescue them, or if things are not catastrophic they'll just write off the losses or let main street investors on robinhood catch the falling knife.