My impression has been that the value leaving the SEC-declared security shitcoins is not stopping at or in some cases even transiting via fiat, but is migrating to BTC and other large cap coins that have not yet been explicitly declared a security.
Many of the security shitcoins (MATIC, FIL, numerous others) suffered a single or double tap over the last couple days without the rebound that BTC, ETH and other unnamed coins have experienced.