So also when the market is down to some extent, the person with $30 may likely loss more because of the money is small. Blockchain has the minimum amount one can invest if am not mistaken but if your amount is too small may be difficult to make easy progress.
What do you think about my advised to him?
If this is not the last $30, with which he hopes to improve his financial situation through bitcoin, but just a small amount that he does not mind spending out of interest, then it is quite normal to start with such a small amount. When it's not just an abstract bitcoin, but some amount of satoshi in your own address, learning about bitcoin becomes much more exciting. More expectations that he will understand this in more depth and detail. So I think it's a great start: on the one hand, he won't be too upset when a bearish trend, and on the other hand, it's enough to generate interest.