Why does a true Christian attends a Church?

Don't give up on the Church... for whatever reasons.

A true born again believer will want to be with a community of believers. There is no excuse for a believer not to attend a local church. 

"Everyone who believes that Jesus is the Christ has been born of God, and everyone who loves the Father loves whoever has been born of him."
1 John 5:1

The bible encourages us to meet together and spur one another up. And warns of those who Sin deliberately after recieving the knowledge of the truth. The "meet together" is called a Church. Those who "Sin deliberately" is not part of the Church.

And let us consider how to stir up one another to love and good works, not neglecting to meet together, as is the habit of some, but encouraging one another, and all the more as you see the Day drawing near. For if we go on sinning deliberately after receiving the knowledge of the truth, there no longer remains a sacrifice for sins, but a fearful expectation of judgment, and a fury of fire that will consume the adversaries.
Hebrews 10:24‭-‬27 ESV

Paul's letters are always directed towards the Church. Being "knit together in love", "to reach all the fullness of full assurance of understanding" of Christ. If one is not united with a community of believers, how can one be part of what Paul describes as "Knit together in love" and reach the full understanding of Christ?

that their hearts may be encouraged, being knit together in love, to reach all the riches of full assurance of understanding and the knowledge of God's mystery, which is Christ,
Colossians 2:2 ESV

It is through the Church, which Paul describes as having "Unity of the Spirit", that we ought to "walk in a manner worthy of the calling". It is also through the church, that out gifts are given and exercised through his Grace according to the measure of Christ given to us. How can one "Walk worthy of the calling" when one is not part of that "Unity of the Spirit"?

I therefore, a prisoner for the Lord, urge you to walk in a manner worthy of the calling to which you have been called, with all humility and gentleness, with patience, bearing with one another in love, eager to maintain the unity of the Spirit in the bond of peace. There is one body and one Spirit—just as you were called to the one hope that belongs to your call— one Lord, one faith, one baptism, one God and Father of all, who is over all and through all and in all. But grace was given to each one of us according to the measure of Christ's gift.
Ephesians 4:1‭-‬7 ESV

A true born again believer will want to be part of a local Church so that he remains useful and united with "those who are born again". One can say, "I am not attending any church, but I meet fellow believers up on my own, and that is Church to me".

However, that is hardly the case. The Ekklesia that the Apostles refers to does not refer to a individual believers who collectively meets to catch up. Although deep individual fellowship has its place among our Kingdom friendships, the idea of the early church is hardly individualistic.

So if you are a believer, you ought to search for a local church where you can actively serve and is relevant to your spiritual needs. One that you can learn more about God through interacting with fellow students of the word, and where you can similarly encourage another through your knowledge of the word.