Yeah, 144hz makes a significant difference for competitive FPS games (especially fast paced ones like Overwatch), but I hardly notice a difference when playing single player or PvE oriented games.
Hell, on some games (e.g. Borderlands 3 and CP2077) I actually prefer to play on my 60hz monitor since a smooth 60hz is much more enjoyable IMO than an inconsistent 100-144hz experience. My computer is admittedly pretty old though.