God did not create mankind in order to damn the greater number of them. His mercy is beyond our comprehension.
And while God doesn't want souls to go to Hell, He knows full well exactly which ones will end up there. He Himself warned us in Scripture: "Enter ye in at the narrow gate: for wide is the gate, and broad is the way that leadeth to destruction, and many there are who go in thereat. How narrow is the gate, and strait is the way that leadeth to life: and few there are that find it!" (Matt. 7:13-14) The Blessed Virgin allowed the children at Fatima to see Hell and the massive number of souls falling there "like snowflakes".
The problem is not a lack of mercy on God's part, but an overabundance of rejection of that mercy on ours -- ironically, often at the very same time we distort the nature of His mercy attempting to convince ourselves and others there is nothing to fear. Would a merciful God submit the children of Fatima, St. Teresa of Avila, and other to the vision of the horrors of Hell if there were not a VERY good reason? So that they could use their experience to warn others of the very real danger.
"Beware of false prophets, who come to you in the clothing of sheep, but inwardly they are ravening wolves." (Matt. 7:15)