First went to 33 (Renoir) in 1988.
33's problems began with the financial crash of 2007-2008: many expat regulars repatriated, leaving a slim customer base for the expanded number of bars. Add in greedy landlords hiking up rents. No marketing strategy to attract new punters and, especially, short-term visitors to LOS. Reputation for high prices - bar-fines were north of THB 1,500, though Happy Hour drinks in many 33 bars were cheaper than in Nana or Cowboy.
And a less obvious reason: some of the older bars, all technically loss-making, had washing machines in the back room connected to football gambling outfits. Once a lot of that cash-flow went on-line, no call/input for the washing machines.