I thought this was an uncontroversial fact everyone knew, but a two-second search on drug-related crime would answer your question, with many links. For example:
"In 2004, 17% of state prisoners and 18% of federal inmates said they committed their current offense to obtain money for drugs [...] In 2002 about a quarter of convicted property and drug offenders in local jails had committed their crimes to get money for drugs [...] Among state prisoners in 2004 the pattern was similar, with property (30%) and drug offenders (26%) more likely to commit their crimes for drug money than violent (10%) and public-order offenders (7%)."
https://www.bjs.gov/content/dcf/duc.cfm
> I'm not necessarily in favor of criminalizing drug trade, but it stands to reason that absent that "line of business", criminals would be under higher pressure to make money otherwise.
Drug legalization is not about ending all crime, and nobody is saying it would, so I'm not sure why you keep saying this. It's about reducing the power of organized crime/cartels, reducing drug-related crime (see above), providing more effective rehabilitation and safety/health, and civil liberties.
> Drug trade at least is more likely to only affect those involved with drugs, whereas these other crimes are more likely to affect "bystanders".
I'm not even sure what you're arguing here, but it seems to be that you think the drug trade only negatively affects drug users and, even more bizarrely, that criminals aren't already involved in "other crimes".