To answer the original question, I rarely give money to people on the street, I do give my time and skills (and on occasion a financial donation) on a daily basis to the homelessness charity I work with. But - that's not to say I think it's a bad thing to give to rough sleepers.
This is a huge subject, but there are a couple of points I would like to make. Some rough sleepers are in receipt of benefits so those who are in Universal Credit areas NEED to have a smartphone or access to a computer in order to log on to their UC journals. (Having said that, three out of every five of my clients don't have mobile phones so my charity keeps a phone at a local cafe for their use.)
There are sometimes very good reasons why people refuse offers of a place in a hostel.
One of my clients is a middle aged man who has worked his whole life. A series of unfortunate events left him street homeless and unable to work due to a health problem. He has no mental health issues, doesn't smoke, drink alcohol or use drugs. I have found him to be scrupulously honest and he has great integrity. He was homeless for months before I was able to help him to access the benefits to which he is entitled and during that time he slept on a bench, refusing all offers of a hostel place. Why? Because hostels are often (not always) places where people with mental health, drug and alcohol problems and chaotic lifestyles are all together under one roof and he would have felt unsafe. During his time on the streets he never begged, but accepted the cash that people kindly gave him. His income from benefits is £73.10 out of which he has to pay for his utilities, clothing, maintaining his (tiny) bungalow and buy food. We are now in the process of making a PIP application with him and without the ongoing support of the charity he would find it almost impossible to sustain the tenancy.