If drugs were legal there wouldnt any cartel activity associated with it, maybe no powerful cartels at all, so this is stupid logic

Perhaps, but right now--as it stands--there is cartel activity associated with it. And funding violent cartels for any reason should be illegal, for the same reasons that funding any violent organization should be illegal.

The alternative of having a square job and funding the US military via compulsory tax payments kills and tortures an order of magnitude more people than the cartels, if you want to follow the money in this line of reasoning.

Furthermore, the destruction caused by the individual use of meth cannot reasonably be attributed to anyone other than the person who willingly purchased, acquired, and ingested the substance with full consent.

The difference being that if you don't buy drugs online voluntarily you won't get jailed. If you don't pay your taxes you, eventually, will.

It's not moral to ask citizens to pay taxes, but it's not immoral to pay taxes: you do it because it's the least harmful option available to you.