that is assuming the market is a closed system, but it's not.

there's constantly new buyers entering the market, who also want a share of the pie, but the pie is very limited, so the more people want a share, the more expensive the shares become.

Sure, a lot of bears lost money, which made a lot of bulls a lot of money (for the first time in years, at this scale at least), but a lot of gains also come from new investors.