Therefore, he should invest five, ten, or 15% of that $100 in Bitcoin and keep the rest invested in local currency or gold as an emergency fund so that he can use it when needed.
Investing like 5-15% of the $100 in Bitcoin and the remaining percentage ( probably 75-95% in gold or local currency)may sound smart but it may not really be the best idea especially for people in countries with high inflation rate, where the value of their local currency keeps dropping on a daily basis. And the implication of this is that the money you have today might buy you lesser and lesser things as day keeps rolling by.
Gold may seem stable but it doesn't grow as fast as Bitcoin does overtime.
If you understand Bitcoin well you will notice that it is better to push up your Bitcoin allocation to maybe 30-40% due to its high appreciation rate.