First of all I want to tell you that avoid asking short or one-liner questions because it makes it harder for the reader to answer you and they look low effort and might not get you serious replies. If you explain your thoughts in detail It can help you get useful answer.

But regarding your question I don't know how you want to build a better future? Let's assume you Want to build a better future using bitcoin. So if you have a low-income and don't have discretionary income coming then first and foremost you should reduce your expenses as much as you can so you have discretionary income. Then part of that discretionary income should be saved for an emergency fund so you dont sell all your investments in bitcoin if there is an emergency and the rest should be invested in Bitcoin and It can be as little as $1. If your monthly income is let's say $100 then $70 should be used for expenses $20 saved for emergency fund  (till you have reached a comfortable amount) and $10 invested in Bitcoin. If you do this for around 5-10 years consistently then I believe you will be in a better financial condition than you are now.
 ( If you have more Monthly income you can get more profits and you should take these examples as percentages of you income I.e 20% of your income for emergency fund etc)