Therefore, do you think that a source of income must be steady enough for years, before one can be financially free or rich or very wealthy, depending on the source(s) of income?
As long as a source of income can help someone to live his/her life happily then that's a good source of income and that type of source can help that person to get wealthy if he/she gives more time to it. However, I still prefer to have multiple sources of income as a single source can not a sufficient for lifetime and that's why it's better to have at least 4-10 sources of income if possible to live life happily without any financial worries.