Jesus knows that these people, in spite of their words, don’t believe in Him. That is, they haven’t come to Him for eternal life.
Did they come to Him? Yes, they did; they followed Him across the Sea of Galilee. But they didn’t come for eternal life, and so they didn’t receive eternal life.
Those who come to Jesus, who believe in Him, must believe in Him for the salvation and life they need, not lesser needs. Those who come for eternal life finds that He meets many needs. Those who come other reasons find that He meets no needs at all