This graph supposedly compares "Democratic Budgets" and the Republican Alternative based on spending as a percentage of GDP between 1980 and 2080. As you can see, Democratic spending is, as they say, off the charts after about 2060.
Now I think it's perfectly fine for Paul Ryan and the House Budget Committee's Republican staff to make whatever crazy assumptions they want about Democratic spending. No one has to take them seriously. But I don't think they can say that this is "based on CBO's Long-Term Alternative Fiscal Scenario" unless the CBO has actually done an analysis that runs through 2080. As far as I can tell, the Congressional Budget Office hasn't done any such analysis. But they have scored the Obama budget through 2019, and it looks like this:
As near as I can tell, Paul Ryan and his staff just took the CBO projections that ended in 2019 and drew a random line, extending upward at about a 45 degree angle, until 2080. There's no real attempt to make it look scientific.