Not so much regretted but more a 'dunno why I bothered'
A former colleague kept coming for advice re a new bike, he avidly listened to all my advice...why you shouldnt buy a £100 BSO, why a £230 bike would be so so much better, why a BSO would sap the energy and desire from you, why one would last longer, be more enjoyable ride, etc etc etc...he just soaked up all the advice, asking asking asking questions.
A week or so later, he proudly arrived at work...on his £100 ToysRUs BSO.
He used it a few times, then it was consigned as most BSOs are, to the depths of the shed I suspect.
Ah well....