Why do Catholics have sacraments?

The sacraments were instituted by Christ to share Himself with us in different ways. They are spiritual reflections of the natural life and connect important moments in Christian life. (1)

There are seven sacraments that fall into three categories; Initiation, Healing and Service. Baptism, Confirmation and the Eucharist are the ordinary means in which we enter the Church and are the sacraments of initiation. Penance and Reconciliation and the Anointing of the Sick are the two sacraments of healing. Matrimony and Holy Orders are the sacraments of service due to being directed towards the salvation of others. (2)

The Eucharist is unique amongst the sacraments because all the other sacraments lead towards it. (3) The other six sacraments shape, form, and prepare us for receiving Christ’s body through the Eucharist.

Citations: (1) ccc 1210, (2) ccc1534, (3) St Thomas Aquinas, Summa Theologica