Timing the market is virtually impossible. I've believed that Trump would be bad for the US economy overall, but when to pull out? And even more important, when to put back in? You pull out too early and miss potentially massive gains. Assuming you time the withdraw perfectly, you wait to long to put back in and you miss out on the recovery.

I should have pulled my 401k (retirement plan) on Jan 1. I didn’t. I lost 17% since then

Jan 1 is an arbitrary date. Why Jan 1 for your measure? trump was elected on Nov 5th and inaugurated Jan 20. The S&P500 closed at 5782 on Nov 5th. At its peak since then it was at 6144 (Feb 19th). Jan 1 was a holiday so the market was closed anyway, so I'll assume you meant Jan 2 which closed at 5868. By that measure the S&P500 has only lost 4.2% from Jan 2 to now. I understand your portfolio likely doesn't match the S&P500 perfectly and you have more exposure in some sectors and less in others.

Will go back in maybe June.

It may be worse then, it may have recovered. No one can know. If it is worse then, you'll be buying on the cheap. If we've had a recovery you will have lost out because you're out of the market when the recovery occurred. Looking at past historical recoveries, I can tell I would have NOT guessed the recovery was going to happen at that moment. That tells me I would be equally bad at predicting when the next recovery will occur.

If you are close to retirement, you should have withdrawn perhaps 5 years of living retirement expenses already from the market years ago into boring safer bonds or even straight cash (you would have missed out on the 35%ish increase in value from being in the market the last two years though). If you're far enough away from retirement, then this is the risk that comes with volatile investing. If someone doesn't have the comfort with this amount of risk, I completely understand that, but this is where the larger gains come from. Investments with little to no risk also offer little to no returns.

The TLDR, I'm not smart enough to time the market. I don't have confidence in those that claim they do.