I’m not a fan of Mr. Osteen. One of his sermons advised “Christians” to avoid those people who “drag us down,” e.g., the poor, the sick, the elderly, the mentally-ill, the unemployed, the addicted, etc.

In other words, all the people that Jesus associates with!
However…celebrity preachers like Mr. Osteen can be and ARE a “stepping stone” for many, especially the “rich and famous”, to a genuine encounter with Jesus Christ.
These rich and famous people are unlikely (and often unable because of security issues) to walk into a neighborhood church. But they will meet the celebrity preachers in various venues and the Holy Spirit can (and does) use those meetings to spark interest in the rich/famous person, and to stir their heart up and help them get interested in doing more research and reading about Jesus.
This can lead to repentance and a true salvation with Jesus, and even to involvement with a local church! (There are genuine churches that attract and retain celebs; e.g. St. Malachy’s in NYC.)
And you don’t have to be a celebrity to be brought to God by celeb preachers. People sitting in hotel rooms or at their home flipping through the channels can hear a message by Mr. Osteen and be touched and convicted that they need to attend to their souls and get things right between them and God.
The Holy Spirit doesn’t need Catholics to accomplish His Holy Work. He can work through the strangest of people and circumstances to lead people to Jesus.