Well, from what I've seen the tax cut for normal folk didn't quite produce the commercial 'spend' most thought it would. The rich have pocketed it and not provided 'business growth' (surprise) as claimed.
Add to the deregulation letting business shit through sensibility, the war on US money abroad and China tariffs - notably even walking back the recent imposition of tariffs having little to no effect on the markets - it's a powderkeg.
I didn't think it would truly bite until gone 2020 and he was potentially out of office, but it may be closer than imagined.
And we haven't yet had the proper fall out from the tax cut either with the wealthy's long term benefit, yet low to middle earners being hamstrung quickly given how it operates.