It was me!
I no longer play poker professionally. I made a living from it from about 2005-2015. 2014/15 was tough though, my first big losing year. Games at mid stakes became 99% pros and the progression towards a purely math based approach was not for me. There was also an influx of bots that year that totally killed my enthusiasm and i could see the writing on the wall. I dont know if the situation has improved as i havent played for 3 or 4 years.
For this hand it would depend on the opponent but against a nobody i would probably bet ~$50. He has a lot of suited connectors like 89 67 TJ T9 in his range most likely where hes been hoping to hit the draw and now its come to the river he feels invested and will hope you had a draw which missed and will most likely call it off really light. If he had a strong hand like a set he would raise the flop as its quite a drawy flop so really the only hands i would worry about that beat you are AT and KT. If he has 56 so be it.