Even due someone is investing in Bitcoin for the short term or the long term, it is advisable the person should have a source of income so that he/she will not rely on selling his Bitcoin holding to solve his life challenges. Fomo can also make someone to sell his Bitcoin holdings because he/she invested in Bitcoin to get some profit in an estimated time but when the profit doesn't come and the price of Bitcoin dips, that person might be forced to sell off his Bitcoin even at a loss.
You're right, some Invested in bitcoin as their one and only last means for financial breakthrough and all minds are on it, what we should have done is to make sure that bitcoin Investment is not the only thing we do, we have to create time and efforts on other assets to complement each other because bitcoin may not be as this always on the bullish and we may needed to sell while the market is unfavourable at dip all because we are in need of money to carter for other things in demands.
Actually there is a saying that putting all your eggs in one basket is a very risky one because if anything should happen to the basket all the eggs are gone, so relating it to what you are saying, however you are correct because as an investor or a business man is never an ideal to have only one single investment because if anything should happen to it, you will be hit back starting from square one.
So as a bitcoin investor in as much as bitcoin is one of the best and reliable investment I will not encourage someone to have only one source because we know it takes a longer time before seeing a profits on your bitcoin investment since you are holding.
Mate, are you trying to say that we should also invest in altcoin? So that our eggs will not only be on Bitcoin investment. It is never good to invest in altcoin because you are not the dev of the altcoin, and if anything wrong happens at the back end you will not know. Investing in altcoin is just like someone playing gambling and you will lose your money if you are investing in altcoin because altcoin is a pump-and-dump token, that is after your money. As far as crypto is concerned, there is nothing like Bitcoin because you will not only make a profit from your Bitcoin investment, but Bitcoin gives you total control over your money, no third party will decide how you will use your Bitcoin, and you can also use your Bitcoin to send money to your family members staying abroad.
So perhaps having other source of income will serve as an appetizer that will take care of your daily needs while your bitcoin investment is up and running.
When I mentioned "source of income" what I meant was someone going into Bitcoin investment should have a means of survival either by having a good business or a good pay job that will allow you to freely invest in Bitcoin and also take care of your daily needs so that you will not depend in your Bitcoin investment to solve your financial issues.