Satan lies. It is really easier to serve God.
Everybody likes to hear what he wants to hear. And there are always enough false prophets around to tell folk that everyone is a law unto himself, can go his own way and do his own thing. But this is simply not true.
There is not a man alive who serves only himself. The scriptures teach us that everyone serves either God or Satan. "Know ye not, that to whom ye yield yourselves servants to obey, his servants ye are to whom ye obey; whether of sin unto death, or of obedience unto righteousness?"
Romans 6:16
"Ye are of your father the devil."
John 8:44
The devil first tries to sell us the fanciful notion of neutrality. Failing at that, he switches stories and declares, "Well I suppose it is true that you have to choose to serve either Christ or me, but I am going to tell you right now that anyone can see that it is easier to serve me!"
Another lie. It is never easier in the long run to serve the old Father of Lies. It is, rather, certain destruction for body, soul, spirit, mind and emotions to work in Satan's employ. He covers his yoke with silk or scarlet, but it is iron underneath. And the iron soon wears through.
By contrast, our Lord does not try to hide the fact that there is a yoke in serving Him. What He does offer is a wooden yoke instead of iron! What He does say is, "Take my yoke upon you, and learn of Me...for My yoke is easy..."