I don't know your age, but as I've gotten older a consistent observation is that vices grow tend to grow with time and we tend towards becoming the older versions of the people we hang around. The social heavy drinking of our 20s becomes the solo heavy drinking of our 30s and the alcoholism of our 40s.
It's rare to see 70-80 year olds with a casual cocaine habit, and of the people I've known who have been interested in cocaine - the consequences caught up to them by the time they turned 30 with a consequence peak in their mid-20s.
I've seen the use of "party drugs" lessen or cease as people I know get older. It gets harder to fit those drugs into your life when you have increased responsibilities and fewer opportunities. Opioids are not party drugs for the most part. Alcohol is obviously a party drug, but like opioids it can become an acute addiction and a maintenance issue (even more so than opioids due to the uniquely dangerous withdrawal symptoms). A drug like cocaine is, to me, similar to molly/ecstasy. It's not fun to do maintenance amounts or to do a lot solo. So use seems to wax/wane with lifestyle. A pattern I have seen a lot is people who used/abused cocaine and alcohol frequently when partying, eventually stopped with the cocaine, and continued on as alcoholics into their 30s/40s/50s.
One interesting things about cocaine addiction is it has one of the strongest genetic/hereditary links of any addiction...
Maybe a dumb question, but would a 70-80 year old be able to use cocaine without dying? If you're not using it often enough for it to be a problem, you also probably don't have much of a tolerance. I would think anyways.
Using a huge amount of cocaine could kill anyone, but a moderate amount can be tolerated by anyone without preexisting cardiovascular problems. That might rule out a lot of people 70+, but certainly not all. Like with most recreational drugs, most of the risks come with using large amounts or chronic use. Remember, these are substances used by tens of millions of people every year and have been for decades if not longer. They may not be FDA approved (well, some forms of cocaine are) but they are known quantities (well, minus the black market impurities).
It's rare to see 70-80 year olds with a casual cocaine habit, and of the people I've known who have been interested in cocaine - the consequences caught up to them by the time they turned 30 with a consequence peak in their mid-20s.