If your friends are no longer your friends just because you transferred to another world, they were never your friends in the first place. They are just people you are acquainted with.
If your FC doesn't continue to welcome you in joining its events just because you've left so you have a chance to get a house, they're not a FC worth joining. My FC cheers on members who leave for opportunities they want, we stay in contact through Discord and they're always welcome to join FC events.
You do not lose anything that you've earned in game other than an apartment, and apartments are available all over the place on Dynamis. You'll even get back the gil you paid for the apartment so you can buy a new one.
At most, you have to do some inventory juggling to make room for the furnishings you remove from your apartment. It's truly not bad as some make it out to be.
Still, I hope that you get lucky in the next lottery so it's not a decision you are forced into making.
As for those who are complaining they can't get a specific upgrade, it's hard to feel much sympathy for them when there are others that have been unable to get a house at all. First SE needs to solve the basic supply problem so everyone is able to get a house. Once that's done, the issue of upgrades can be tackled.