I think now is a great time to remind everyone, like sync's developer, Lemmy's developers need to be paid too! The amount of time all the devs put into making lemmy exist, in my opinion, should be worth some of your money. If you can afford it, donating to the people who develop lemmy and/or the people keeping your home instance up will accelerate the incredible growth of lemmy!
If all the big instances go away through lack of financial support, they're going to find out they paid $130 to swap Sync memes with the 3 people left.
They might contribute to an existing instance sure, but I doubt they'd host. There's no real financial incentive for the profit driven to host a Lemmy instance unless they charge for membership and I doubt even Sync users are naive enough to pay twice for something.
I left because of how reddit treated the 3rd part app Devs, suddenly forcing them to cancel subscriptions halfway through the year. (They could have given the Devs a heads up, but chose not to.) I left because of the libel that was being spread about a dev. For me, it wasn't that they wanted to charge money to use reddit, it's how they went about it that made me leave and not return.
Of course, they also forgot about blind people and moderating tools. They then kicked many mods for voicing their opinion and/or participating the blackout, even if the subreddit in question was in agreement with them.
I don't see Sync doing any of that, so please speak for yourself on why the migration happened.