Hi,
I am in similar position as you are - a few years in application security including pentesting.
I have decided to try bug hunting. I started off by being very enthusiastic, but quickly became demotivated. If you are ok with spending a lot of time and effort to do research, find bug, compile report just to be told that that bug has been already found by someone else but not yet fixed (which you kinda have to take their word for it) - then sure go for it. For me the experience has been pretty frustrating. This might be a good value for the companies to have a crowd hacking their sites - however I find it very unfair and disrespectful for researchers’ time to have to chase something - which has already been found - and you don’t know that!
Yes, there is an OPTIONAL program that bugcrowd has where companies may choose to adopt where they have the option to disclose some of the bugs that were fixed. I think it is a good step forward, however its optional and so not many choose to adopt. And even if adopted companies would not disclose bugs unless they’ve been been fixed - and in many cases that can drag on based on their business priorities - so you are still in the dark.
So, if you have a lot of time on your hands which you don’t mind wasting, go ahead. I suppose this can be beneficial to learn and practice ethical hacking. But since you are already a seasoned professional - I don’t know if that would be of any value to you. If you still decide to try - my advice is to forget about the low hanging fruit and concentrate on more difficult to find bugs and keep your fingers crossed you are the first one 
For me - I decided that I just cannot be motivated to look for bugs when I don’t know if they were already found or not.
Good luck!
