Yes, XEM to BTC and then to USD using gemini.com and I did it in Dec 2017 and January 2018 which luckily turned out to be the right time anyway. Same with Ethereum, NXT and a few other things I had.  I paid the taxes early too in March both for 2017 and 2018 -- estimate tax for 2018--  (which was like 20% capital gain tax).

I still have some BTC and XEM and ETH but I am not planning to sell anything for the next 3 to 4 years,  even if the price goes back to $1. Maybe 3 or 4 dollars, then yes, but otherwise I am good.