It does include everyone but if your income is over a certain amount you don't get anything. It's quite common in tax systems to be exempt or be required depend

It does include everyone but if your income is over a certain amount you don't get anything. It's quite common in tax systems to be exempt or be required depending on your income level. UBI is in addition or on top of your income (if any). UBI isn't necessarily income in that it's a person's sole income. In my country people get unemployment benefits if they are laid off, welfare if really bad, food banks, dental care for kids under 18, daycare for kids under school age, medical care (but still carry insurance), some school's pay 70% tuition depending on the circumstances. So really UBI would combine all those into one, if you don't need it that's great but if you do there it is. Sure some people would live off it but it's no different than doing that now.