> When there's stablecoin, you just put your dollar in stablecoin before they print the money, the dollar inflates, stablecoin goes up proportionately,

Printing fiat makes stablecoins denominated in the currency lose real value, not gain in it. (Stablecoins denominated in a different currency would gain nominal value in the printed currency, the same way direct holdings in the alternative currency would.)

So, no, to the extent easy money policy makes people rich fairly directly, holders of stablecoins denominated in the currency would not be among the beneficiaries.