[curtains]

I would fold. This isn't quite the bubble so there is no great reason to believe he's raising small with the idea of folding. (If there were two stacks under 500, then I would probably push) Also your image is probably that of a big bully when you move allin, due to your giant stack, which may make some more likely to call.

Also you will often be able to steal relentlessly in the future in situations where your opponents have shown zero strength at all. I always prefer to steal against zero strength than some.