That's a wholly different argument though.
People who earn more can afford more, sure.
Being single without dependents doesn't stop you earning well, indeed it's advantageous compared to those raising children.
But all things being equal, (ignoring the advanages that single people have that helps them earn more) a single person paying for one person expenses is worse off than a couple, no children pooling money, yes.
But better off than a single parent paying for 1, 2, 3, 4 or more children
And better off than a couple where only one person is able to work.
And better off than a couple where only one adult works and one adult provides childcare for 1, 2, 3, 4 or more children.
And better off than a couple where both adults work and they are supporting 1 or more children.
Probably also better off, if working, than retired people relying on state pension, disabled people on benefits, those without jobs....
So in the various family types, one person supporting one person is more fortunate than pretty much every family type apart from couples without children.
Yet on and on and on they whinge about how hard done by they are...