To the contrary, legalization has the implication of regulation, taxation, and increased government oversight. Politicians fight it because they believe it is politically expedient for them to do so.
Legalization means allowing the people to choose to engage in an activity, thus shifting to the permissive oversight role of government. In this case, the citizen has the implicit trust of the government in that he may act as he chooses toward the previously-banned item. If this second route involves more parts of government, so be it, but at least it returns some autonomy / choice / liberty to the individual.
Depending on what politicians do, we may be stuck in a bad in-between state where you have the full police state going strong to prevent non-authorized dealing as well as the oversight / regulation function.
I fully trust that the politicians will continue to pursue power at any cost, including the liberty of the people and the sovereignty of the nation.
Opposite of how we all like to think of the tech industry, politics are slow, clunky, and bureaucratic — for good reason. It takes a long time to go from "random HN/reddit commenters talking about legalizing drugs" to "politicians talking about legalizing drugs."