For a scammer behind a coin with a $50m market cap to have walked way with $50m, they would have needed to have sold all the coins at that valuation. In some cases, this may have happened. In many others, they will have sold some coins at that valuation, and others at lower valuations as the coin collapsed. In a few cases, all the transactions may have been "wash" transactions (aka, selling a coin to yourself under a fake name), and the scammer may have received nothing.
It's hard to know how much a scammer profited without digging into it, especially in the crypto space where wash transactions are so easy to get away with.
All metrics related to "crypto total market cap" are based on dubious circulating supply metrics, when the reality of this is many times higher, even though it is an accounting nightmare regardless.
Next up, most coins actually did sell all of their free float / circulating supply in exchange for a more liquid currency.
So yes, the $50million projects actually received $50m in usd/btc/eth AS WELL AS granted themselves a sliver of the new currency, akin to private equity and every share company ever.
It is double plus good, and scammers are currently walking away with that. But if they are smart, they make their new coin valuable because an even greater windfall awaits and then that means it isn't a scam project at the current threshold of legitimacy.
> But if they are smart, they make their new coin valuable
Citation needed. :)