in the short-term while proof-of-work phases out (limiting transaction fees) and the volume of unmined Bitcoin continues to diminish (hopefully bringing price stability to BTC and the market as a whole)
Neither of these are correct BTW. PoW/PoS has nothing to do with transaction throughput and BTC will never be stable.
Getting burnt by scammers is as good a reason as any to avoid crypto altogether. Even if testnet currencies aren’t material and don’t represent real losses, getting scammed or worse (i.e. having your identity exposed) will disincentivise users in the onboarding process from continuing their dive down the rabbit hole.
If real crypto can't be made secure (see earlier "almost got scammed" article) then it's unrealistic to give people a secure learning environment. Arguably the testnet should be even scammier than the real cryptoverse so that people can either toughen up or give up before real money is involved.