Treasure island/stalk market achievement question

[Tiffany]

I have never been to a treasure island. I read that if you go to one and do the max bells/turnip trick(pick up a turnip on the ground and sell it in that town for max bells) that it causes the cornering the stalk market achievement to glitch so u can no longer complete it. I was just wondering if anyone knows if you do the max bells thing when u have already completed the achievement will you lose it? Thanks