If the bolded were true, it would be secure already. The fact is that the leadership of the Dem party already voted for the border wall while Bush and Obama were president, at least giving it lipservice, if not money. The fact is, they hate Trump more than they want to open the government or close the border.
And there is zero support for your claims. As was pointed out, when offered a decent compromise -- making the DACA provisions permanent, the Democrats were willing to give Trump $25 billion (or even as high as $50 billion, by some estimates). Of course, as has been pointed out, Trump himself is the one that shot that down (after agreeing to it) because he was called by Conservative Media, such as Fox News, "Amnesty Don." Trump has no one to blame but himself that his wall isn't already funded.
Sure, the Democrats have agreed a wall is beneficial in various areas -- even giving funding for some 700 miles of wall during the Obama administration. Agreeing that walls can be helpful in areas where people illegally cross the border makes sense. It doesn't make sense to build wall in the middle of barren, arid land where no one is trying to cross the border -- which is what we'd being doing by building another 1200 or so miles of border wall (which is what Trump has claimed he wants). It's about like me trying to claim that Republicans are hypocrites because they want a wall on the Southern border but not the Northern one -- odd the "double standard" by Republicans.
Now, if you want the real truth, neither political party appears that interested in actually solving the issue -- even though both sides bloviate about border security. If we were really serious about fixing the illegal immigration issues, we'd be punishing businesses (and even individuals) that hire illegal aliens -- without jobs here most of these immigrants won't be coming to the US illegally. It doesn't do them any good to come to the US if they can't find work. At the same time, we'd make an enforceable guest worker program. The truth is that businesses (including Trump's, as had made the news recently) depend on that "cheap illegal immigrant" labor to keep their costs down, and won't let their bought and paid for politicians entirely fix it.
So, no, this has nothing to do with "Trump hate." Rather, it has more to do with the Democrats making compromises three different times, with Republicans and with the "blessing" of the White House, to fund the government -- twice Trump has, after indicating he'd sign the legislation has backed out. The middle time, they made the compromises based on a promise to promote debate on DACA legislation in the Senate, something that still has not happened (largely because Trump refuses to sign any such bill -- despite promises in 2017 that he would sign DACA legislation if Congress passed it).
It's not on the Democrats that Republicans, and in particular Trump, are not negotiating in good faith (pulling out at the last moment), or that Republicans (again, mostly Trump) isn't living up to promises he made. The Democrats already compromised on the current package to get the government open, with the White House signalling Trump would sign it. Why should they have to re-negotiate the deal that was struck now, merely because Trump, after the deal was done, added new requirements?
