Index investing and DCA is the best that the majority of people can do to become more wealthy. But this only works if you have big enough income
I disagree. You can still do dca method even if you do not have that huge amount of income. The idea that you cannot invest unless you are wealthy is just wrong.
If you know how to manage your finances well and you are able to save some of your income to direct to great investments then surely it is possible.