The first verse of the Bible reads, "In the beginning God created the heavens and the earth." Then, it continues, God blessed the seventh day and called it holy. Why? Because he rested from his works (Gen. 2:3). This actually sounds strange, because God was not exhausted. I think he wanted to tell us something else here: That he definitely takes pleasure in his works and enjoys them. So in Genesis God is described as the one who created the work and also loves it.
The decisive advantage of the professionals is obvious: they can finance their mission or mission project themselves. Jesus said unequivocally, "In vain have ye received, in vain also give!" (Mt 10:8). Professionals do not have to rely on donations. They do not have to report regularly to friends or partners to convince their supporters that their gifts are well invested.