They were concerned more about their pigs and their business, rather then the eternal life, Jesus could give them.
They did not realize, that Jesus is the source of their provision and business.
They thought Jesus is ruining their business. They did not realise, the eternal value of believing in Jesus.
They thought that they provide everything themselves, and missed the real source of provision and eternal life, by asking Jesus to leave them.
Today, there are people, who do not want to give their life to Jesus, because they think it would be necessary for them, to leave many things in their lives, which they find valuable.
But God never wants to take anything which he thinks is valuable for us. Just the opposite, God does give us many valuable things, and he never wants to take anything valuable from us.
Let Us Study the Bible 