If you believe that earnings should be tied solely to labour, you are not a capitalist. Capitalism changes the form of labour that is not consumed. It reinvests it. Like taking the profits from Oil, Gold or Corn and investing them in infrastructure, factories and sportsfields. If all you do is spend what you earn without investing some, you have very little flexibility to absorb the shocks of life. A 'bad season' can wipe you out.
Most of our 'capital' is the cumulative effort of thousands of years of learning. We earn because of our ability to speak to each other. We earn because of the constitutions of our countries. The trade between our countries and others. There are no self-made Billionaires. There are no self-made tradesmen. No man, or country, is an island.
A Universal Basic Income can be thought of as a dividend on our Social Capital. It can also be viewed as 'Retained Earnings' that are reinvested in people. If it frightens you as a 'Communist' idea because it lets people earn off the efforts of others, you are not a Capitalist.
Communism tied the means of production to labour. 'From each according to his ability, to each according to his needs'. The incentive to produce more or create a life was stripped away, because the decision of who needed what ever was produced was stripped from the individuals.
A Universal Basic Income instead empowers individuals, and communities, to look up from the stresses of trying to survive to figure out their needs. To respond to however they are motivated. To create meaning for themselves and their communities.