That is a fair point and I think a lot of people would use that kind of reasoning against UBI. But I still think more people would want the money for themselves.
There been polls about it. While the majority thinks (around 80%) "if others get UBI they become lazy and stop working". If you ask the same people how they would act, they say they would keep on working.
People think why more negative about others than about themselves.
I guess only those who would see a massive benefit for themselves would support the idea. Everyone else would fear to lose more as he gains.
But the positive change with healthcare isn't as obvious as it would be with UBI. UBI would be a much easier sell.
I would argue it's the opposite.
It's way more easy to explain the benefits of healthcare as of UBI.
Free healthcare is spending money for a single purpose.
It seems to be manageable and shows a simple to explain benefit. - you don't have to die.
UBI is way more complex.
At first you have to explain why everyone gets the money. No matter if they earn $0, $50,000, or $1,000,000 a year.
Next you give the money without a clear purpose. No one has to bee in real need... this means people could spend it for everything - holiday for example. And I guess many are willing to finance your health treatment, but not your holidays.
Cash is seen as something different to services.
Some will argue they aren't willing to finance more families with many children... they already have 5 children and she is pregnant again? They only fuck for the UBI and are too lazy to work. - in Germany you get at least €150 per month and Child (that's nearly nothing), but still people argue this way about families with a lot of children.
The benefits are hard to explain... happiness and less stress. We are so used to have no happiness but a lot of stress that we can't think about a world werew it would be the other way around.
Instead of this we focus on possible negative effects.