It's really very easy, honestly.
My laptop is my work life and my personal life.
I spend easily 100 hours a week using it not-as-balanced-as-it-should-be between the two.
I don't buy them because I need something new, I buy them because in the G4/Intel era, the iterations were massive and even a 20 or 30% increase in speed (which could be memory, CPU, disk -- they all make things faster) results in me being more productive. It's worth it for me to upgrade immediately when apple releases something new, as long as I have issues with my current device and the upgrade is enough of a delta.
M1 -> M2 wasn't much of a delta and my M1 was fine.
M1 -> M3 was a decent delta, but, my M1 was still fine.
M1 -> M4 is a huge delta (almost double) and my screen is dented to where it's annoying to sit outside and use the laptop (bright sun makes the defect worse), so, I'm upgrading. If I hadn't dented the screen the choice would be /a lot/ harder.
I love ThinkPads too. Really can take a beating and keep on going. The post-IBM era ones are even better in some regards too. I keep one around running Debian for Linux-emergencies.