Yes, it is unrealistic as there is no guarantee that promoting these start-ups projects can give you money to sustain your daily needs as a human being and especially for your family. But there is an exception, If you have a business or you are a freelancer then it might be an ok option for you.
Without exception, you have a business or you are a freelancer, you also need to spend a lot of time on the business or the field where you are talented, can not spend too much time promoting a full time bounty campaign. Bounty campaign is not an option for the long term because income is too dependent on luck, sometimes we will get back a pile of rubbish after a while we work, wasting time and effort, so we should think this is just an extra income in the times we are free, the main income is still the current job, that is more realistic