I don't like to see veterans homeless either, makes me sick too. But I don't blame D.C. Some veterans choose to be homeless, some are junkies, some are too proud to apply for benefits, and some just don't know how. D.C. has created benefits for veterans. The VA administer those benefits. It is easier than ever to get benefits and get more of them.
The VA paid out $76.52 billion in compensation benefits alone FY 2017:
https://www.benefits.va.gov/REPORTS/abr/docs/FY17-Compensation.pdf
$5 billion in non-service connected pension:
https://www.benefits.va.gov/REPORTS/abr/docs/FY17-Pension-Fiduciary.pdf
$12 billion in education benefits:
https://www.benefits.va.gov/REPORTS/abr/docs/FY17-Education.pdf
Guaranteed $188 billion in home loans:
https://www.benefits.va.gov/REPORTS/abr/docs/FY17-Loan-Guaranty.pdf
This does not include healthcare, which is free for veterans who cannot afford it. D.C. cannot keep track of every single veteran and make sure they are taken care of. D.C. and the VA are not perfect, but they do more good than they get credit for.