Soldered RAM doesn't degrade faster than socketed RAM from heat cycling.

Not in normal use. Both types handle thermal cycling just fine within their design lifetimes.

The idea that soldered RAM (BGA chips on a laptop motherboard) wears out faster from heating up and cooling down than socketed DIMMs is mostly theoretical fearmongering. BGA joints are engineered for thousands of thermal cycles. Laptops run hot, but they also don’t experience extreme temperature swings like industrial equipment. Socketed RAM has its own failure modes — corroded contacts, loose sockets, bad connection from vibration — that are arguably more common than solder fatigue in normal consumer use.

The real difference isn’t reliability; it’s repairability. If soldered RAM fails, you can’t just pop in a new stick. But under typical conditions, both will outlast the usefulness of the machine. I’ve seen ten-year-old MacBooks with original soldered RAM still running fine. Focus your worry on cooling and dust, not thermal cycling.