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.
You really have to find the right audience in order to make money from referral programs. If you are not popular enough and if you don't have enough reach to influence them to sign up using your referral code or link, most likely you'll not really profit by doing referrals. You'll just waste your time and effort.
However, if you have an interactive audience and you are persuasive enough to get them sign up using your link/code, then you'll most likely earn big through referrals. I've known people that made referrals as their main source of income simply because they have the platform to do so and they are very much determined and eager. You just really have to be patient in this kind of generating income because not every referrals will be successful. Some might not push through, some might be detected as invalid or abuse if you'll do self-referral and it will be detected by the system.
Most influencers and streamers are using both referrals and affiliation links which is advantage on their part because they get to earn while promoting and doing the things they want. Although I don't really recommend making it as main source of income and relying on it fully because you will never know when will these programs will be put into halt. It's always much better to have a fall back.