This is actually a very good question. We may never know for sure what their true motives are for doing this, but here are some possible reasons nonetheless.

One possible explanation might simply be that the tobacco industry is one of the few major industries that's still relatively WASP (or more generally white gentile) dominated compared to most other major industries, whereas the marijuana industry (a relatively new industry) is mostly controlled by Jewish elites (this explanation is purely speculative and I don't have actual data on this, so feel free to correct me if I'm wrong).

Another explanation might be that the elites demonize smoking tobacco because it's a typical European pastime with colonial origins which is historically associated with (conservative) "white male culture", and also has the potential to boost testosterone levels and curb obesity, whereas they promote marijuana because it's associated with leftist subcultures like the hippies, modern black culture and LGBT culture as well as "woke culture" in general, and also makes people dumb, apatethic, docile, weak, unwilling to reproduce and generally more receptive to leftist ideas and sensibilities.

Then, of course, you have the most woke/normie/PC explanation that decades of research have simply shown smoking tobacco to cause severe and potentially lethal health problems such as lung cancer, whereas there isn't conclusive evidence of smoking marijuana on its own without tobacco added to it causing significant physical health problems. However, this explanation fails to address why the same governments and other institutions that have been going after tobacco for a while are now also starting to crack down on vaping (which is relatively harmless, and doesn't have anything in common with tobacco aside from the fact that both contain nicotine). This explanation also conveniently ignores the extreme addictiveness of marijuana combined with the many psychological health issues it can potentially cause (which tobacco, let alone vaping, could never cause), by seletively solely focusing on physical health.