It doesn't make you happier, it's just that you became unhappy and the new bike was necessary to temporarily make you happy again.

Happiness is binary. You're either happy with where you are or where you're heading or you're not.

> It doesn't make you happier

It sounds to me like you haven’t rode a bike in a long time. I recommend you try it and get back to me.

I own several and have ridden thousands upon thousands of miles.

When I got my first bike as a kid, a cheap "mountain bike" with 24" wheels that probably weighed more than my current road bike, I was at maximum happiness. I was not at only 40% happiness because it didn't have a carbon frame or a Di2 groupset from the future. I was at 100.

Later when I got my first road bike I was at 100% happiness again. But nothing can make me happier than I was with that first, heavy bicycle-shaped object. It might equal it but it's impossible to surpass.