Referral bonuses or earnings arent something that you could rely nor expect into because not all people or users who registers under your name are big depositors or players which means it would really be just normal that you wont really gain something if those users arent playing.
I beg to differ. I know many people who make a living out of referral programs and they have made it their main job.
You need to know where to promote your ref links (choose your audience) and how to promote it to get the best results. Sometimes, you even need to invest some money for paid ads before you can start earning.
If you are into streaming or have a big blog/group/channel then better opt for affiliate programs than ref programs.