Whether you are a Reddit refugee (I am one) or just randomly stumbled upon Lemmy and decided to join lemmy.world, welcome to the Fediverse.
If you have been here for long enough and settled in and now finally feel comfortable with Lemmy, I highly advice you to move to smaller instances. I just newly left Lemmy.world to join Lemm.ee.
We need to capitalize on the decentralized nature of the Fediverse and Lemmy instead of having everyone joining one instance. This will benefit the admins of Lemmy.world a lot as they would not have to deal with such a high amount of users. It also leaves room for new users to join and have a good experience rather than an experience filled with server outages where they will give up on Lemmy.
Playing devil advocate, here : you can expect the life expectancy of bigger instances to be slightly to significantly bigger, if anything because their admins feel more responsibility due to the number of users depending on them. That argument does not hold if we’re comparing using a big instance vs self-hosting, though (the life-expectancy of your self hosted instance may be smaller, but if you shut it down it means you’re not interested anymore in the fediverse, so no big deal - except maybe for the holes you leave behind you). And anyway, I’m not sure better life expectancy is more important than making sure the fediverse stays decentralized.
That’s a good argument for bigger instances, but not one for using the largest one. Lemm.ee, sh.itjust.works have more that 2k members, sopuli.xyz and reddthat.com have 600 members, based on your argument their expected life expectantly is as long as Lemmy.world