I guess investing money for future is a must, at the same time, it should not be done at the cost of totally ruining the present life, it should be a balance, life is so unpredictable so like we need to save for emergencies as well, a planning for old age when we can have good amount of money we can spend on health and other necessities, and we should also spend during the present times to fulfill our needs and wants now as well but surely in a limit.

I guess the number of income source matters less than how one manages their earnt money, like one can earn from a source and then invest that money in the stocks of various companies and get dividends from them, saving up an emergency fund, trading with a comfortable amount in free time. But surely more than one substantial income source is good to have so one doesn't get much pressure to hold on to a single job or income source that can make life easier.