1. You know what you like
Having many different dating experiences and partners gives you the opportunity to know what kinds of things you like in a relationship. Maybe one person does something sexually that you love but would have never thought of otherwise. Or a person communicates problems by telling you a day later, to cool off. You might have never thought of that before, but it helped your relationship
2. You know what you don't like
Basically the same as the previous point but the opposite. Someone does something you absolutely hate, now you know for next time.
3. You understand what you deserve
Let's face it, dating around will give you shit people every once in a while. But it will also give you the most amazing people you ever met. Those people treat you like gold, now you know for next time that is how you should be treated. You can't put up with the shitty stuff because you've had the best.
4. Don't really have the need to want to date around
The number of people I know that wishes they dated someone before their previous partner is crazy. These people found their one right away, they have had everything with their current partner. But, they have wondering eyes and wish they had been with someone else.
5. You will have many experiences
Having experience is like you're a wise owl, you have knowledge about relationships and will be able to bestow it on future you as well as friends. It also kind of goes hand in hand with knowing what you like and don't like. Having experiences just gives you knowledge.
6. You know what heartbreak feels like and how to overcome it
Heartbreak is the single worst thing that can happen. There are different kinds, but one from a significant other is different than any other. It always teaches you a lesson. You end up changing a bit of who you are. At first, it's devastating, but then you eventually realize you don't need anyone but yourself and become more self-reliant than relying on others for self-love.
7. You won't put up with bullshit
It's easier to see the red flags if you've been through them before. It's easier to know how you want to be treated.
8. It's easier to tell your partner anything
It gets easier with practice. Telling your partner your weaknesses, what's going on in your head, and being completely vulnerable comes with practice. You either get experience with people who don't say things, which ruins relationships; or you get the relationship where you are completely honest with each other.
9. You may be shielded, but the right person will tear the walls down
Sometimes because of everything you guard yourself. But eventually, when you trust someone enough, you will put that guard down and let them in.
And finally... number 10
You realize all you need in life is a great set of friends.