It's all relative. I still like to ride fast, but what counts as fast for me now is not what I would have considered fast ten or twenty years ago.
Just yesterday I hit 38 mph on a descent near where I live. It felt fast, but Strava tells me I hit 46 mph on the same hill right after entering the 55-65 year-old age bracket. Average speeds are now usually in the 15-16 mph range on moderately hilly routes, down from around 18 mph just a couple of years ago. I tell myself that it's because I've been riding steel bikes instead of my carbon bike, but deep down I know it's the engine that's changed.