It's never too late to start investing in SEO and no one's position is guaranteed in search results, meaning that you can take out someone's position no matter how long they've kept it for.
It is, however, going to take work and consistency as well as a killer strategy to beat your competition if they're already performing well.
You're going to have to perform better than them across a number of SEO elements and that's completely achievable, it all depends on how much time and effort you put into it. Time to start taking back that organic traffic that could be yours!