This guy is telling you in 5 years time, you'll hate him. Because he honestly likes you. One more point, unlike womans' brains, mens' brains are still developing into their 30's, while our's is more developd by the time we're into our 20's. OP, is that what you want from a boyfriend? As a 21 year old, I went out with guys 11 years older than me.
In college I dated 'older' men too.
Why do 35+ guys date 20-year-olds?
These are actually kind of shitty, hard years where you're just starting to become a real adult and get bruised a lot and need to figure out who you are. Have fun. If you can learn it at 20 it will be like a relationship super power.