If you consider what the energy output is used for then that would be a different story since that's a different equation when it comes to carbon emissions. Couldn't disagree on the fact that it's negated if used for a selfish stuff but that's a societal or individualist problem I think. Maybe if we got the real numbers on how it's used and how much these renewable resources offsets in carbon emission, you might reconsider if you're not right.
Bitcoin mining is just one of the few examples, but there are definitely more than what meets the eye. These are generally unpriced effects and it would be terribly difficult to put a number to it.
I think when it comes to good or better for the environment stuff, I think that it's a subjective thing, a dam wouldn't be a good thing for a salmon who goes upstream to breed but for humans it's good since it helps them preserve water and create artificial watersheds to foster wildlife and fisheries. Regarding nuclear waste handling, I don't think it's difficult, it's more on politics because there's a country in Europe(I forgot the name of the country) that has a very good handle on their nuclear waste by turning a small island into a nuclear waste storage, plus developing your nuclear power means cheaper electricity and fossil fuel companies don't want you to do that.
Water stagnation isn't good in all of the cases. Dam helps to prevent floods, minimize risks of wildlife lost but you also need to consider the landarea being cleared and the construction of such dams. Dams aren't just affecting aquatic animals but they have a cascading effect on both the surrounding settlements and wildlife. Nuclear waste actually decays in quite a long time due to their halflife, and they are generally unsafe to handle and sooner or later, the risks of us running low on space to hold these waste could be quite real; can't have it too close to the settlement, regulated nuclear exclusion zones, etc.
Politics and big oil is one thing, but there are realistic constraints on top of those.
Depends, if there's too much dam built on a river, I think that that's when the benefits outweigh the costs like what's currently happening in the Mekong River, China has 12 dams built in it while the other countries that are crossed by that river on has a total of 2 and now those at the lower end of the river are experiencing droughts.
Every construction of a dam comes with a significant trade-off. I'm not saying that we can't build a dam but there should be proper evaluation done to it to ensure that the reasons that we have are concrete and sound.