This is ALL about 2020. Do you think Trump really gives a shit about people? He made a signature promise and if that wall is not even partially built by the end of this year he will lose much of the base he has. $5B is peanuts, everyone that has a clue about what Washington spends on BS knows this. All it is for is to allow him to say "see, we got some money to build the wall but now we need to do more, reelect me in 2020".
If we weren't living in a dystopian version of America the mature thing would be to reopen government and get a deal done that includes ALL the outstanding issues on immigration and border security. It Trump and his acolytes weren't so arrogant they would realize that a large deal would likely incorporate money for border barriers/protection/more boots on the ground etc. Immigration reform including DACA, quotas, clear cut protocols that can't be skirted etc is more important than a wall at this point. Trump can get his funding if he gives people what they need. This would entail a long negotiation but would be worth it. We are, however, living in this dystopian scenario and because of it, neither side will budge.
I would gain a lot of respect for the first people to come out and say let's open the government and get to work on REAL solution. If they do not do so by the next budget, shut it down again (if you're Trump I mean).