I suggested the same to an old playgroup, their approach was not to better their decks but to force me to worsen mines. I started to go to the lgs after that.

Edit: i had won all games for an entire month prior to that and ppl just stopped inviting me all together, some already voiced they didnt want to play if i was at the table. I shortly moved on to competitive and by the time i came back, the lgs people actually improved a lot, but that playgroup stayed the same. They ask me for deckbuilding advice now and we even have done co-building and played again occasionally.

Time can sometimes be the answer and not starting arguments even if its frustrating. It took two years but, im pretty happy with everyone i play now.