If God really exists and prayer has power why have I not won the lottery and married a porn star?

Dude, marrying a porn star is a terrible idea. You marry someone who looks like a porn star.

Because everybody that plays the lottery prays that they will win it. See the problem with that? As for the porn star, God is saving you from extreme jealousy.

(Galatians 6:7, 8) States: Do not be misled: God is not one to be mocked. For whatever a person is sowing, this he will also reap;  because the one sowing with a view to his flesh will reap corruption from his flesh, but the one sowing with a view to the spirit will reap everlasting life from the spirit.

And(1 Corinthians 6:9, 10) Make clear: Do you not know that unrighteous people will not inherit God’s Kingdom? Do not be misled. Those who are sexually immoral, idolaters, adulterers, men who submit to homosexual acts, men who practice homosexuality,  thieves, greedy people, drunkards, revilers, and extortioners will not inherit God’s Kingdom.

(Galatians 5:19-23) Add to my comment RE: YOURS) Now the works of the flesh are plainly seen, and they are sexual immorality, uncleanness, brazen conduct,  idolatry, spiritism, hostility, strife, jealousy, fits of anger, dissensions, divisions, sects,  envy, drunkenness, wild parties, and things like these. I am forewarning you about these things, the same way I already warned you, that those who practice such things will not inherit God’s Kingdom.

Those eager to do God's will and follow Jesus Christ will work hard at cultvaing the fruitage of God's spirit which is love, joy, peace, patience, kindness, goodness, faith,  mildness, self-control. (John 13:17) If you know these things, happy you are if you do them.(1 Peter 5:7) while you throw all your anxiety on him, because he cares for you.

You have not accomplished these goals because God exists and answers your prayers, "no.". Try praying for someone else to win the lottery and observe what happens.

I think you missed the part that God answers the prayers of his people. If you don't believe he exists, he isn't going to be granting your wishes. When you do believe he exists and are guided by the Holy Spirit, you will learn how to pray.

Which porns star

No True Scotsman fallacy in 3..2..1..

Oops, too late.

"You ask and do not receive, because you ask with wrong motives, so that you may spend it on your pleasures." (James 4:3)

"But he must ask in faith without any doubting, for the one who doubts is like the surf of the sea, driven and tossed by the wind. For that man ought not to expect that he will receive anything from the Lord, being a double-minded man, unstable in all his ways." (James 1:6-8)

You ask for the wrong motive, you do not ask in faith, and you ask for things that are contrary to God's word.

Also because anyone who prays for those things is a selfish idiot whose priorities are almost hopelessly corrupt.

Just a possible reason, you know. Something you might want to include in your considerations.

You misunderstand prayer if you think it's a wish-fulfillment service. Doesn't work that way.