You can wager money on almost anything, including whether Trump does or doesn't manage to serve out his term. At the UK betting house Ladbrokes--you can bet only on sports in Vegas--the odds of Trump leaving office before the next Inauguration Day, by impeachment or resignation, are 10/11. In other words, if you think Trump will be forced from office before the voters have a chance, and are willing to put ten dollars behind it, you will draw out only eleven dollars when it happens.
So bettors are not very bullish on Trump surviving. Maybe they aren't all experts on American politics, and have overlooked the salient fact that the House of Representatives, currently run by Republicans, would have to adopt articles of impeachment, and that the Senate, where Republicans also are in the majority, would have to vote to remove him.
On the other hand, people are betting their own money, and there's ten dollars thinking Trump's toast for every eleven that think the world will be interpreting his tweets for at least another 3.9 years.
I'm guessing this particular betting market was flooded with new money after the FBI director testified the other day. It's an ominous sign--and, it seems to me, an underreported one--that Team Trump's talking points shifted perceptibly after Comey confirmed that the Administration is the subject of an FBI investigation. Before, the "whole Russia thing" was "fake news." And they still are saying that, but in the last couple of days we've also heard for the first time about certain shadowy figures, fringe members of the Trump campaign who of course were unknown to Trump himself, "hangers-on," people whose only role was to be let go once someone up the chain found out they were on the payroll. It's not a real long stretch to surmise that these nobodies are the operatives the FBI will have the easiest time implicating in criminal acts performed with the Russians.