How does someone build wealth who has little to no money to begin with?

Personally, I would make sure I have sufficient backup for a few months of expenses should I be out of job. Also, I need to have sufficient insurance for any unexpected situation. Only after that would I start investing my excess funds.

Little can grow. 1 drop of water can become 1 pail of water if the drops stay in the pail. Better to start w little than nothing. Time can help with accumulation. E.g. if you top up 100 every mth for CPF - SA - the amount does grow, doesn't it?

Emergency funds is a must in case you need it. and then start investing bit by bit.

I feel you can save and Invest at the same time. Maybe start with low-risk investments so that you don't get a shock when the value of your higher-risk investments becomes negative. I started out by buying Singapore Savings Bonds, I still bought SSB last year.