Wonder Cure !

Obviously not true. But I love the stuff anyway.

does it actually cure cancer ? and help with other health problems or is it a blag so they can just smoke it ?

From what I've heard there is positive research on the anti-cancer effects though I've not read them myself.

CBD, cannabidiol, is a non-psychoactive compound being touted for all sorts of benefits; I can only attest to it certainly lessening my back pain. The regular THC-heavy stuff helps me with depression, stress, and anxiety, where no pharmaceutical antidepressant has worked; using it regularly also seems to lessen my back pain, so I just use the psychoactive stuff.

There are undoubtedly those who use it all as an excuse. But no, it is a very useful plant.