The Baggies lost 1-0 at Old Trafford on Saturday in a match that was completely overshadowed by VAR controversy.
Bilic’s men were awarded a penalty by referee David Coote in the 46th minute after Conor Gallagher was tripped by Bruno Fernandes.
But the official was asked to check the decision again on the pitch side monitor and then decided to overturn his decision.
That sparked fury from Bilic as well as Albion’s players and fans with it appearing certain Gallagher had been fouled.
Speaking post-match, United legend Rio Ferdinand and retired referee Peter Walton said the original decision should have stood and that a penalty was the right call.
In the end, Ole Gunnar Solskjær’s side won thanks to a controversial penalty of their own from Bruno Fernandes.
But it means in their last two outings, Albion have been a whisker away from securing results against Tottenham and United – with Spurs winning at The Hawthorns thanks to an 88th minute Harry Kane goal.
And Bilic believes his team is now much more resilient, with the Baggies having been accused of being too easy to play against earlier in the campaign.
“There should be optimism,” Bilic said when asked how the team moves forward following the heartbreak of United and Spurs. “We should have more points. We deserved a point at least on Saturday.
“We should have gone one up. That’s exactly what I told the guys. Of course, we were disappointed, but we have to use it to keep momentum and confidence.
“Make no mistake, some of these players and also as a team, we’re still entering some games with a little bit of ‘do we deserve to be here?’.
“We have to find the confidence in the game. If we start good, then we continue good. But we are good, we are a good side.
“If we continue like this and sacrifice like this, if we continue to train like this and play like this, the wins will come.
“We’ll have chances in every game because we’re going to be hard to beat. That’s us now.”