Doesn't require Craigslist or buying used. You can get a boring but totally functional commuter bike with disk brakes and 1x9 speeds from Specialized for $1k o

Doesn't require Craigslist or buying used. You can get a boring but totally functional commuter bike with disk brakes and 1x9 speeds from Specialized for $1k or less (Sirrus or Sirrus X). Similar models from other big bike brands. Then you have $1k for maintenance over a decade to fit within $2k, which is probably plenty.