The flexibility to test concepts and market demand in real-time let's say a zcash chain is spun up, you can peg in and start using that, it can support a community of apps that want privacy tech natively and they can happily live and trade in that world without diluting the bitcoin network effect and F'ing around with shitcoins.

Not to say there couldn't be rug pulls built here but that's what the user has to decide, leaving the base chain for any L2 requires accepting risk, LN has it Liquid has it, and statisticians have it, just the nature of the game.

If it fails and there's no market demand, people just peg out and move back on-chain or to the next drive chain idea but the base chain just soldiers on.

They can also be a response to bandwidth issues, if on-chain fees are high and slowing down LN, drivechains can come in and provide liquidity and reduce the competition for block space on main chain so fees even out quicker when demand spikes

I also see use for drivechains in being able to build custom chains, could be something simple like bigger blocks and you can I don't know stuff ordinals in there or run application-specific chains like a Bitnames DNS/namecoin thing.

Just see it as a place to F around and find out and let the BTC liquidity flow where the ideas captivate the audience, could be good ideas, could be bad ideas, but it attracts developers and VCs to experiment in Bitcoin. You bring the funding and the brain power into the ecosystem instead of them wasting time and resources building another solana or EOS etc