i bought my active subwoofer system ~15 years ago; upgraded the drivers from the factory about 10 years ago, upgraded the active x-over to dsp speaker/room correcting x-over about two years ago.
i bought my preamp about twelve years ago, upgraded it twice w/factory-recommended upgrades.
i bought my turntable about twelve years ago, upgraded it a couple time along the way...
i bought my fono stage about ten years ago. the "fotm" thing has almost gotten me a few times here, but so far, i haven't succumbed.

i bought my dac about ten years ago; modded it a lot the first year; bought a second one w/different mods a few years ago; i still have both. i have used a couple different transports w/my dac; the one i have now is going on two years. i wish there was something to succumb to regarding dacs, but nothing at anything less than silly prices will make any meaningful difference, imo. i keep looking, tho...
i have several different speakers; i have been listening to the same pair for about a year and a half now. i haven't bought any new ones in about a year. if i had more room, (i live in a studio apartment), i'd possibly have switched out more speakers, or even bought different ones to try. for now, i am still enamoured of my horns, and they're too freaking big to easily move out of the way, if i want to hear, say, my piega's or gemme tanto's. speakers are about the last frontier for me - so many different ways to skin a cat, so to speak, and i want to try them. when i get back into a regular house, this may start up again. but, definitely a reason to shop used - if you want to try a lot of different things, it can get wery expensive buying new.
i have several amps; but i haven't bought any new ones in quite some time. i am pretty-much set now - i have amps that will work w/any speakers i might decide to try.
i listen to a different tuna every few weeks.

i presently have about fifty; they get rotated a lot. i need to sell about half of them, but i find myself too lazy - it's much easier to buy than to write an ad to sell.

ymmv,
doug s.