As Christians, what are we looking for, first in life? To have the Kingdom of God, or to have our bellies full with food?
In John 6:26, Jesus told them, that they should not come to him for his material gifts, but for the things about the kingdom of God.
The sign and wonders which Jesus performed among them, were the part of the Kingdom of God expressed on earth. But they did not come to him because of the signs and wonders. According to Jesus, they wanted something else to eat.
They allowed their belly, to become their idol, placing it of first importance, before the Kingdom of God. They wanted the material first, and then, maybe the spiritual things of the Kingdom of God.
But Jesus said, that it is not the way to come to him.
The way to come to him, is exactly what he said in Matthew 6:33, that we should first seek the Kingdom of God, and then, everything else will be added to us.