Bitcoin increases in value overtime, money decreases in value overtime so they are not similar. Btc is more of an asset than a legal tender which is why it can not be similar to money completely. Although they both hold great importance only that one is more valuable than the other. When it comes to making a real life choice among the two, i will rather go with the 20-80 rule 
You should know that the bitcoin price is very volatile if you don't convert all your money to bitcoin investment, don't forget the risk of unpredictable bitcoin price movement patterns so it's better to invest 30% of all the money you have to reduce the risk if the bitcoin price drops significantly , so both are still the best choice but the use of bitcoin is still limited so you have to make bitcoin as a long term investment.