On the point that UBI will mean 'no one will have the incentive to work hard to get ahead', I would suggest that you look at how pensioners live - that is a good demographic to provide a 'lab' to observe. There are some who get depressed and do nothing but watch daytime TV, but there are plenty of others who get involved in the community or in hobby clubs and feel they are doing more, and more good, than they ever did in their jobs.
On the point that costs will rise to meet this new source of income from the taxpayer, yes that will negate the whole point of it.
We have to take away the question: where is the money going to come from?
It seems to me that the only way to do it, to eliminate homelessness and hunger in our country - and they are an obscenity if we are to consider ourselves at all civilised - is to separate the citizens' entitlement from the free market, and that means providing the UBI in units that are incommensurable with money. Units such as calories, kilowatt-hours and megabits per second - yes, the beancounters can do their sums as a hobby but leave them out of it. It would then become an extension of the voluntary sector, and people can choose to divide their time between the public (voluntary) sector and the private sector which can still be as rampantly capitalist as you like.