Many people tells BTG will become another failure. What is the base in this? Can this be true?
It depends how you define "failure". Will it beat legacy bitcoin? Most likely not...
But will it have some users, miners, etc.? Yes. Their proposal to use equihash as an algorithm will give them some ASIC-resistance for a while, which could mean a small rush back from some CPU & GPU miners.
The question is for how long will this drive last? No one knows, but if the question is 'will it take over the legacy chain', I wouldn't put my hopes in that.