I'm not saying they're necessarily right to view each of those House seats as safe, but Trump clearly wants to get some things done. There's no reason to think he's being careless with the House majority. Even if he's taking a bit of a risk, it has to be a calculated one.
That goes double for the Senate. Even if he views a 3rd impeachment as grist for the mill, he definitely doesn't want impeachment charges to reach a Dem-controlled Senate.