yo! my ex teacher (pencen already) open a class at her house, each sub cost 150 per month per student. each class consist of about 30 - 40 student. she teaches 2 sub - Bahasa Malaysia and History for SPM students (form 4 & form 5). imagine if she got 120 student (about 4 class a week?)
300 x 120 = 36000 with just 4 class week maybe at most 4 hours per day (2 hours history, 2 hours Bahasa). Tell me if this is not enough for you.
Another story, my friend (parent rich people) go to private tutor who teach accounts, physics and chemistry . i dont know how many time per week but it cost about 2000 per student. each class only max of 5 student. imagine that. so being a teacher does pay well.
another story - i heard that these days, if u work as a gov teacher, u cant do tution. i dont know the details. just heard only.
Good luck!