Buying the top 20 coins is a good idea but he must analyze one by one to find the coin but most people just buy when the price start moves without analyzing so that make them buying a wrong coin. Experiencing losses and profits is normal but if you can learn from your losses, you will improves your knowledge so that gives you more chances to pick the right coin.
But no safer trading especially if he doesn't have much skills so the first thing he needs to do is learn trading, understand how to analysis and pick the coin. But Bitcoin trading may be safer because he only needs to buy and hold then sell when the price increases and he can rinse and repeat the process and increase his profits.
That's the problem, I have seen a lot of people who made these mistakes, and while that is expected at this point, it's not really ok because if you just buy without looking at it and just jump on whatever is trending at that point, you might be too late and fail.
This is why we are saying buy right now when it's going down so that you could profit, because if you buy when it's going up, then the going up could stop and it can start going down and you will lose, but if you buy when it's going down, then it's already down, you will profit quicker.