Players with high levels at the lower tiers only become concerns when they participate in RTG or challenge tournaments or skins games. And if they win the RTG or WGT free tournaments they tend to get promoted. Some of them do enjoy playing alternate shot or match games, but since those generally are only for pride, again not much of a concern.
In the mobile game things are a bit different since so much involves useless coins. Not sure what the advantage of sandbagging there is, but I am sure it happens.
Where have you been meeting these high level lower tier players?