To the contrary, had he vetoed this bill he might well have won and defeated an attempt at override, kept his integrity, avoided humiliation which he is experiencing now, kept his conservative base, put the Rinos on notice that he intends to govern as he campaigned, forced both Rinos and Democrats to go on the record, and saved the balance of his presidency.
Instead he has shown the white feather, not just accepted but affirmatively endorsed a law which is contrary to virtually every promise he made as a candidate and which leaves him in a condition in September when he can do naught but sell us out again.
If he had in fact been defeated in an override of his veto after having taken his case to the country, exposed the contents of the bill to the people, exposed the waste and corruption, and give them hell in the style of Harry Truman and Ronald Reagan he would have at least survived to fight another day even if he were to lose the vote. He could have roused the country. He has forfeited that option now.
How can he now be heard exhorting us to make America great again? He has lost credibility among those in his base who actually believed his promises. That in a president can be a mortal wound.
Fake News. Trump can de-fund the ACA with an executive order, just as Obama used EO to fund it.
With the veto he also could have gotten more of what his supporters want.
Even a single item, a cut to planned parenthood, removal of the no funds to be used on the wall provision, etc... and he could have claimed victory just for moving the ball.