Ok for a more intelligent reply here.
Your standard boots are going to come in a bunch of varieties, they could be made with eproms, flash roms, custom pcbs, original pcbs, wires, daughterboards, and more, all of which of course contribute to the quality of the boot.
Eproms are erased by light but if covered and in a cartridge case there is no chance of accidentally erasing an eprom, these will last just as long as solid roms and are in fact used in many official SNK carts. Data rot will set in a time period of like 50 years, something that's not worth worrying about.
Flashram is not going to get erased by light, and similar rules for data rot apply.
Wires and bad solder jobs could cause a problem in bootlegs but in general a clean well made bootleg (like my ghostlop) will last you just as long as a regular cart.
Buying boots of older games is in no way supporting those that made the boots, since all the boots in circulation were created when the game was new, there is no profit in creating bootlegs of old games.
Buy boots if you wish, they work just fine, and if you don't mind, I'm glad you're playing the game.