For some people who only putting in $100 per month will be low and others even $100 impossible. Like if you compare cost of living now in NY vs Tunis and where you currently live and intend to retire too.
The idea of deferring some pleasure now for the expected receipt of security in the future is a good concept.
I think a good long term strategy is investing into index funds but not at the expense of basic needs now.
Perfect. Deferring pleasure now for the future is sound advice and important but not if you create hardship now.
The point is, everyone's situation is different and there are no hard and fast rules. Every situation is as unique as the individual.