Do you even know why the Berlin Wall was built, Perfect?
On the actual subject, it's been made very clear that Trump won't be getting his wall. His meeting that he arranged has fallen through and the Mexican government seems to have no intentions of rescheduling. However, if the wall were to be built, what honestly are the downsides? It opens up plenty of jobs on both sides of the wall, makes illegal immigration a slight bit more challenging, and we get a giant fucking wall. Those are all bonuses to me.
And no, the wall wouldn't ruin the economy if the money spent went into American business. Surprisingly enough, spending money makes the economy better, not worse.