However it will 100% cost you more money then you will earn, if you ever earn any. If you want a feel of it online you can try go4sc2 or any small online cup even in the small 25 or 100$ event you will probably not win more then one series if your MMR is around 5000 (so I guess master 1-2).
But if you just want to compete it can be fun go for it, just go into it expecting to get smaked around quite a lot. I only played in one Lan (Ets 2016) and at diamon 2 at the time I was clearly outmatch by everyone but still had a good time.