Yeah, I will. I wasn't suggesting that I should continue using mine past 10 years (looking at the datestamp on it, it was actually made 3 years before I bought the house, so it is 17 years old). Just noting that many things around my house seem to be working well past when they should.
Looks like Walmart even has one that is the same brand (First Alert) as my current one and appears to use a compatible mounting plate for $7.67, so should be an easy replacement.
Statistically, you are a very very lucky human.
The replacement cycle of a smoke alarm has a built in safety factor because it was designed by engineers.
If your life was hanging by a rope, you're betting on it's absolute strength not it's rated load.
Smoke alarms are ten bucks a pop at Walmart. You can pick up a CO alarm and a box of waffles while you are there.