Soldered RAM doesn't fail more often in three years.

No.

Over three years, the failure rate of soldered RAM (BGA) and socketed RAM (DIMM/SO-DIMM) is basically the same — very low. Manufacturers like Apple and Dell test these joints for thousands of thermal cycles. If it’s going to fail, it usually happens in the first few months (infant mortality), not three years in.

The real difference is what happens if it fails. Socketed RAM? Pop in a new stick. Soldered RAM? You’re replacing the whole motherboard — or the whole laptop. That’s expensive and annoying, but it doesn’t mean it’s more likely to fail.

Don’t avoid a laptop just because the RAM is soldered. The bigger risk over three years is the motherboard dying from a power surge or liquid damage, not the RAM itself giving up.