Computers are like lightbulbs, and laptops are the extra fragile kind. They burn out. I've never had one more than five years, and after year three I just assume it could fail at any moment -- whether it's an SSD crash, a swollen battery, or drivers breaking after the next OS update.
If you replace machines every three years, like I do, you're not necessarily paying for performance -- you're really just paying for peace of mind.