The lesson here is that no employee who has started a new job should ever tell any of his colleagues at the new place of work that he has any cryptocurrency and that he is into gambling. And especially not the employer. And even if at the new job his new colleagues start discussing issues of the crypto industry and gambling, then simply do not participate in this conversation or avoid direct questions on this topic.
And then such guy gets fired after probationary, because he does not fit the team. I would instead talk with colleagues about crypto and gambling, if they talk about that, but give general information, nothing that can show that I am good at them. Being silent and secretive also does not work well. As an employee, it is recommended to follow what you post or interact with in social media. A person might be a good and hardworking guy, fits well in team, but posts that he is radically against or support something, and employer can take that information as a reason to fire him.
Well, of course, this is an option to participate in conversations about cryptocurrency and pretend that you are an absolute sucker in these matters. But then, firstly, you are lying, and secondly, you can screw up and be suspected of insincerity. And this is also a negative scenario for working in a team.
As for the control of the employee's social networks by the employer, I think that this is now almost always done, apparently secretly. And in life, when dismissing an employee, the employer does not necessarily state the real reason for dismissal. The reason may be completely different from what the employer says. And this is all connected either with the unacceptable productivity of this employee, or with other factors obtained from the analysis of information about the employee and the potential risks of the employer if he does not dismiss this employee. I think this is almost always done by the employer quite reasonably and substantiatedly and on the basis of factual verified data.