I don't think its certain he'll get a second term. I certainly hope not. Obviously Biden is better than Trump, as were Obama and Hillary. The fact that you use such a sarcastic response is interesting. There are people out there who suffer endlessly because the American public go from cycle to cycle electing a representative who doesn't give a shit about them. To those people life under Trump probably isn't that different to life under most of the previous Democrat presidents. It's important to get rid of Trump, for America, because he is giving a free run to GOP corruption but mostly because America's status globally is quickly disintegrating. However if by electing Biden everyone thinks that everything becomes fine then you enter the exact same problem post Obama. To be honest the only real way for America to stop this repeating pattern is mass demonstration demanding a change to how politics is ran in their country. However I don't see that as a possibility. The idea that Trump and the GOP is the problem is funnily enough actually the problem. The problem is the system that has allowed this stuff to fester. Whether you like it or not the Democrats are a problem too because for some reason whenever they've got into power they have never pushed for the systematic changes that are so blatantly needed. The democrats don't need to 'stop the GOP' they need to alter the system so that corruption on both sides isn't allowed to happen. Step one: stop letting money rule your politics. Whenever a politician comes along that even hints they want to do that they get attacked from both party's propaganda wings.
The fact is that a democracy means 'for the people'. If you keep needing to rely on a certain subset of people to help elect your 'choice' then maybe it's time that you start listening to their needs. This doesn't mean that you need to elect Bernie, it simply means that you can't expect to have his followers help get rid of Trump and then ignore them until you cry foul at the next election they fail to turn up to.