Especially when we're less than three years into his first term.
The Republican tax cuts and the Trump administration's deregulatory agenda very likely did add something to the economic growth in the US in the last few years, yes - however high the cost to its long-term solvency may turn out to be, and however unequally the benefits of that extra growth are divided among Americans. Perhaps without those, the rate would've been half a percentage point lower, or even a full percentage point.
But the general tendency of growth is just a continuation of a trend that started much earlier, and they deserve no credit for that. In today's globalized world, periods of growth and periods of recession happen on a global scale, and no single country can drive or reverse them on its own. At most they can somewhat outperform (or underperform) the general global trend. Obviously that also means that if a recession does happen in the near future, it won't be entirely or even mostly Trump / the Republicans' fault, though his trade wars are likely to be a contributing factor.
But of course the 'insane agendas' of the hard-left Democrats are currently being emboldened very much by the way the Republicans slavishly follow the worst, most corrupt and most offensive president in American history - meaning that for a huge number of Americans, literally anyone on the Democratic side is still a lot better than Trump, even if they would much prefer a sensible Republican to somebody like Sanders.
And to answer your actual question, if Trump gets impeached, the Republicans could run somebody like Pence or Haley who has enough ties to Trump to inherit most of his support, without disgusting the majority of the country in the way Trump does.
As a near-retiree whose income will be coming primarily from your investments, of course you'd have other incentives than younger people who need to get it primarily from wages - and they won't see much wage increase with a president like Trump who hands out massive tax cuts to corporations and just a few crumbs to his voters. But as I mentioned above, once the recession that has been hanging over our heads for a while materializes, it will only make a rather limited difference who is president at that time.