Your Professor's hate for crypto is a classic example of hating what you don't understand. As a person with such wealth of knowledge, one would expect that he researches crypto just as he would his academic work. Yes, there's the probability of getting scammed, not just trading Bitcoin, but every other online business out there. But with the right safety measures put in place, you might as well be in this space for years and never get scammed.
Those who were scammed are either newbies in the crypto world or just being reckless about knowing if the transaction they are doing is legit or not. There are even people who would take the risk of being scammed because the amount of money that they can get from that transaction is quite big so even if there is a high probability of losing money, they would just go with the flow and then if scammed, they would just rant and then regret that they get involved in the first place.
If you don't want to be scammed then do due diligence first and spend your time first in checking the site and here in the forum as well as to what is the feedback of the people about the site. As much as possible, use the sites that most of the people are using and has good reputation but always check the URL because a lot of them are phishing sites.