For those worried about BTC longevity, this is likely your answer.

The same reason South Korea (at least temporarily) placed a ban on crypto & ICOs -- the government needs time to understand it and put systems in place to account for its effect on the economy.

A basic way to answer this question is to answer:

1. What percentage of his monthly income does he want to set aside for investing?
2. From that amount set aside, what percentage of his investment funding does he want to allocate towards highly volatile investments? Starting out, I'd say 10-20% of your investment amount allocated towards something higher risk is not unreasonable. From there, he can increase or decrease this percentage based on his total level of income, how much of his other debt has been paid off, and his level of understanding of cryptocurrencies in which he's investing in.

But as far as an investment, if he doesn't understand what he's investing into, he shouldn't be investing more money than he can afford to lose anyways.

Bitcoin is just now becoming something that the general population is becoming more aware of. And by general public I mean a large population of people who are far less education in Bitcoin, cryptocurrency, and security. But yes, people will continue to churn out of the market as long as hacking/scams continue to be an issue.

If the market were to fall, it might eventually be due less to scams and more to hacking. I think if there's anything that can kill a market that exists purely based on speculation, it would be the continued inability to protect investments from hacking.

I understand the logic behind his argument in saying it's "useless", in that Bitcoin doesn't follow the laws of economics. It's currently a system that is being fed based on speculation of "it growing", while not producing anything to help sustain it's growth. In that perspective, yes, it could be perceived as "useless".

Once Bitcoin has a level of utility similar to that of cash, to where it becomes more than an investment vehicle, then I think that's when it makes sense to even the most traditional of investors.