In sum, the claim stemmed from a story by The Atlantic, which relied on anonymous, second-hand reports of Trump's alleged words; there was no independent footage or documented proof to substantiate the in-question comments; and Trump vehemently denies that he once called service members "losers" and "suckers." While it was certainly possible that he said those things, Snopes was unable to independently verify the claim.
If the biased site Snopes can’t verify it, it’s pretty certain to be a lie