There's a reason we're in the situation we're in now. The simple fact is that Democrats and Republicans don't operate by the same rules. When Democrats want change, they trust the system to do what it's supposed to do. They believe in the marketplace of ideas, thinking that truth and justice will win out. By contrast, Republicans do not care how they get what they want. The ends justify the means. When we have a Democratic President, they make up their own rules and refuse to cooperate or compromise. But when there's a Republican in the Oval Office, anything less than total submission is called being an "obstructionist." Republicans expect Democrats to compromise while they refuse to budge.
There are only two ways for Democrats to respond. First, they can continue to play by the rules, and lose ground as Republicans abuse the system to get what they want. Take now, for example, when Republicans are stacking the courts in their favor, speeding up the nomination process to get a Republican in the seat DAYS before the election. This after they refused to even vote for an Obama nominee, on the grounds that a nomination shouldn't be made on the last year of a President's term. Let the people decide, they said. Funny how the rules change when convenient for them, huh? The GOP's lack of consistency or dignity puts them at a significant advantage here.
The second option is that the Democrats say enough is enough, take their gloves off, and start behaving like the Republicans do. They give up any pretense that the system will work itself out, and they do everything they can to increase their power. But if Democrats do that, then Republicans will point their fingers and say that they did everything the Republicans accused them of doing. They will justify the opinion too many people have already been fooled to believe: that Democrats are "just as bad." Additionally, even if we started playing by the same rules, the Republicans would have a several decades headstart. How long would it take for us to catch up, or even gain the advantage? We'd have to get insanely lucky and just happen to have a President in office when a seat is made available. The odds are stacked against the Democrats.
I honestly don't see any way that we can get out of this mess. I wish I could have some hope for the future to hold on to, but we're in a lose-lose situation here. We are absolutely fucked. It takes us forever to make any progress, and it only takes one term for Republicans to undo decades of hard work. Even if Biden wins, so what? Does Biden strike you as a man of conviction, who will push hard for positive change, who will do everything he can to fix our broken system? No. It would be a minor setback for Republicans as they work to repeal Roe v. Wade, increase "religious freedoms" (for fundamentalist Christians to take away everyone else's freedoms), and take rights away from marginalized groups. The Republicans will have their theocratic utopia, and any problems that inevitably arise from that system will be blamed on Democrats for not getting with the program.