In England for example...every EPL team from Manchester United to Chelsea have an Academy and you will get scouted playing for your local team to join an EPL club's youth academy if you are good enough. Even if you are in a tiny number that's good enough for an academy...to then make the step up a few years later to the actual first team is incredibly hard as over 95% don't make it.
becoming a pro football player isn't that hard it may seem like it but if you train hard and concentrate put your mind to it and focus on it it will happen somehow in some way and also play for Sunday league teams and you can get scouted for bigger teams and before you know it you play for a pro team>>JUST TRAIN HARD AND FOCUS<<< (STAY IN SCHOOL COS YOU NEVER KNOW IF YOU WILL BECOME A PRO FOOTBALL PLAYER)
If it was easy, everyone would be doing it.
It's just like any other professional sport. You've got to be good and that requires hard work, lots of practice, dedication, and at least a bit of natural talent. And luck -- sometimes it takes luck to be at the right place at the right time to get noticed.