That's a common mistake among new investors. They don't have proper investment plans, they invest every money they have in Bitcoin hoping to get quick profits whereas Bitcoin investments are usually good for the long term because the price in the short-term is more unpredictable.
That is why it is said to invest only as much as you can afford to lose. Moreover Bitcoin investment is not that you will be able to earn profit from it just by investing and even Bitcoin is not a get rich quick scheme. Bitcoin investment is unlikely to be successful in long term but short term investment can be profitable if you buy large amount of bitcoins at once during dip season and sell it during bull season.
Some even sell properties and other stuff they own only so that they can invest the money in Bitcoin. I believe that shouldn't be done unless they can afford to do that and won't have any financial problems in case the price goes down after they make their investments.
The problem for those who sell their property to invest in Bitcoin and sell other things to invest the entire amount in Bitcoin is that they cannot provide enough money to cover their family expenses. In the end, they have to sell the money they invested in Bitcoin before reaching their goal. As a result, the hopes they bought Bitcoin from the investment were not fulfilled. So before investing ensure your own source of financial income from where you will be able to sustain your investment with the remaining money after meeting the family expenses.