It's an article of faith that cutting taxes will generate manifold economic activity increases, but I'm leery about overestimating this, it's more likely a bounded situation where it works to a point and then zeroes out or starts working the other way outside those bounds, i.e. there's probably a point where those curves cross above the origin point on the graph.
There are a lot of real things that aren't taken into account by one-liners about Reagan's tax cuts. Just to name a few, swings of the economic cycle, technological and cultural shifts in economic activity, demographic changes in the population that have real effects on economic activity, changes in economic strength of our trading partners, and last but not least the fact that our high corporate tax rates have virtually nothing to do with what corporations actually pay in taxes if they are big enough to influence government policy on deductions applicable to their business (I particularly have in mind megacorporation GE, which paid no net taxes the year its CEO was Obama's 'Job Czar' and who off-shored thousands of GE jobs in the same year).