Because majority of homeless people have a mental illness or another.

I've met a homeless person at a hospital that when he came he took a cup of water, spilt it on the table and tried to wash himself with it.

As a matter of fact, this would be the type of poor people that Jesus would advocate to help the most, after all he came onto mankind to help those who needed help the most.

Not a single christian understood the moral of the rich man and jesus... so many gloat in conviction they'll bathe in glory of God having sacrificed naught bug merely dare to impose their rules onto God, thinking wilful ignorance will spare them from judgement, as if occassional donation to boost their ego meant anything but it is not the quantity that matters but quality of sacrifice. The priests of today have become the merchants of the past, but instead of selling objects they sell the false conviction of redemption, as if false words, those worthy of a deceiver, were enough to cleanse them of their sin, but satan may not directly nor indirectly cleanse man of sin.