There's never previously been a significant wall, and the penalties have had loopholes. Those can be closed. Heck, add a private right of action for any citizen as a means of enforcement. That would let not just the feds, but any aggrieved businessperson bring a case. You wouldn't have to rely on federal enforcement in that case.
Anyway, your argument essentially boils down to no deal being acceptible because it always can be changed by politicians. If under the current system we're not kicking them out, how will amnesty make it any worse?
Honestly, what do you think the odds are that a wall would ever be put in place? They've been given the same excuses for years....and will continue to do so.
Absent that, shallow/empty promises to "fix the problem" and revolving amnesty every 15 years or so is all that has been, or will ever be, done.
Perhaps you can understand some psychology, as applied to children. When you set a curfew, or other rule for your teen, and they break it, would continued "amnesty" for any consequences teach the teen to stop breaking the curfew? No, so why have a curfew if it's not enforced? Would you reward your toddler with cookies when he/she hits their sibling after you had told them "don't hit"? No, so why bother having a rule against hitting if you reward them for that very behavior?
Repeated amnesty emboldens and encourages even more illegals to come into this country because they already know that if they can't get it this time, there's another one down the road and in the meantime, they've been "taught" they can ignore the immigration U.S. rules/laws with impunity. And if those laws can be ignored.....maybe they can ignore all the other laws they choose.
When rewards are given out after rules/laws are broken, it encourages more of the very thing the rule/law was put in place to stop.
What's the logic is that kind of system?