I genuinely don't understand the thought process behind holding any altcoin.

Sure, some altcoins have specific use cases to supposedly optimize their "medium of exchange" function on the base layer, like smart contracts, privacy, faster payments, yield, etc. But when you claim to use these altcoins for those purposes, you've already inadvertently made the case why you shouldn't hold on to these coins for any duration longer than needed to complete a transaction or benefit from some heavily marketed utility.

If desired, the most logical move is to quickly use the altcoin for its "utility", then convert the altcoin back to Bitcoin.

But you see the problem? There is no incentive to actually hold on to the altcoin. If there's no rational reason to hold to the altcoin, it will underperform compared to Bitcoin. It will lose the fight for liquidity. An altcoin "money" cannot develop without people holding it.

I don't see the economic, or more importantly, the philosophical, justification for holding on to any altcoin for any significant amount of time, or how it could even compete as an actual money.

They simply go to zero against Bitcoin.