its not imposible if you are a developer..you can make 1 or 2 bitcoin in a month
but trading too will make you earn btc...
if have high skill programing developer is easy can get earn 1 or 2 bitcoin/month
trader with skill perfect and developer is easy can get earn 5 bitcoin/month
you can see gavin anderson(bitcoin developer), another ethereum dev, monero dev, i think can get 10 bitcoin/month still easy