Here's the thing tho': pranks are fun. Developing alternative energy sources is hard work, and what sponsorship does Greenpeace do in that area? Not much...
That, and not any conspiracy theory, explains everything.
I agree: I don't give money to Greenpeace because they're a marketing organisation that raises cash to do more marketing.
But: there is a school of thought that without broad community support, all the hard work won't add up to much.
They might be partly right, I pay more for "green power" than my neighbours do for "glowing-in-the-dark power", and don't own a car despite how much easier it'd make my life. I guess someone's marketing worked on me...
There are people working on alternative energy. They get less subsidy money from the government than the oil industry, which is plenty profitable on their own. You can re-read that sentence if you didn't believe it the first time.
It takes all kinds. Science and PR to protect the science. The political can be very connected to the scientific when the industry threatened with displacement is very politically active.
I'd be really interested to see a detailed accounting of the oil industry subsidies you refer to. When I've looked into this in the past, all I've been able to find are things like the depreciation of capital assets, which, while it could be considered a subsidy, is not specific to the oil industry. The numbers are very big, but that is because the oil industry makes some of the largest capital investments in industry.
That, and not any conspiracy theory, explains everything.