There are multiple factors at play here. In important one is that the attacks happened in NATO waters. For Russia to attack in such a location would be a huge risk, especially when you consider that they could attack the pipeline in their own waters instead.

Also, the existing pipelines run through Ukraine. So if the Nord Stream pipes are permanently out of service, that means Russia has no choice but to pay Ukraine transit fees if it wants to continue selling gas to Europe.

This is why it is absurd for Russia to do this. And equally absurd is the idea a state actor can accidentally blow up the wrong pipes four times. This isn't one single leak. There are four separate ruptures. The location is near a Danish island near Sweden, so it's not exactly in the middle of open ocean where it's easy to get lost. I'm not aware of any other gas pipelines in the vicinity of this island, though obviously I'm not particularly clued up on underwater pipelines of the Baltic Sea. I'm aware of pipelines running from Norway, and Russia might want to disrupt these because they supply the UK and mainland Europe. But if this was their intended target, they were in the wrong sea. Even the most incompetent navy isn't going to end up in the Baltic Sea when they want to be in the North Sea.

Everything points to USA. They said they'd do it, the incentive is there, it advances Western geopolitical agenda at the cost of Russia's, it makes absolutely no sense for Russia to do this and it makes complete sense for USA to do this.