One of the big reasons is this: you're at different places in your lifespan, and are looking for different things.
You may not even realize all of the things you want right now. Do you want kids? Maybe you don't right now. But maybe, suddenly, you'll come to realize one day that you do. By that point, your partner may be too old to have children with you. Do you want someone who you can be active with, and go on adventures alongside? I will tell you right now that your potential partner may not have the vigor and energy that you do.
That said, maybe it can work out and maybe you are contented enough in your life that you can make this relationship work. Given that we don't know much about your age, and whether you are under or over 18, it's hard to say whether or not approaching this other person is out of the question.
My ex had a thing for older guys. Maybe I caused her to discover that, being a younger man lol. For some people, I think there are good reasons for dating an older partner. They are more experienced in life, have lots of stories to tell, and are a lot less dramatic about things. They can provide you with stability and take care of you.
But you have to be aware of the potential negatives as well, and decide if it's worth it to proceed with getting to know this person and flirting with them.
Discussion closed - why not create your own thread?