Thank you Dad, I will now provide the several examples I always provide.
– Tommy Andersen winning TaG Senior heat race and setting fast lap of the race at the SKUSA SuperNationals against world-class factory drivers. Kart was a Kosmic chassis with 2 seasons of national-level racing.
– Ashley Rogero winning national TaG/Rotax races on a Tony Kart that was a couple seasons old, at least.
– Stepanova Nekeel winning the Rotax Grand Nationals in Rotax Senior, running a used $900 Tony Kart frame he bought THAT weekend at the track, after his brand new whatever-it-was was off the pace.
– I snapped my 2014 Exprit that had a year of racing national racing on it after crashing at SKUSA SummerNationals. Put together a new Exprit out of the box and ran within .1 of my lap times on the old kart.
Moral of the story, as long as you care for your equipment, run skid plate etc., a kart should last you at least a season and still be competitive. If you let your frame rails get ground down by bashing over curbs or you crash the thing and have to straighten it a million times, ANY kart is going to wear out.