@ fungal_net said right. We need to provide a basic tool for a basic network configuration. When the dhcpcd package is installed the service itself is not enabled (a contrary of other distro). You need enable and start by yourself.
Anyway, if you don't want it just do not enable it. And like said fungal_net, if it already enable for whatever the reason just do:
# 66-disable -S -t <tree> dhcpcd
replacing tree by the good one and you will don't see a dhcpcd daemon running anymore.