That's a forced celibacy that never exists in Scripture of God's Word, and it's therefore unbiblical. Why do people follow this stuff?
If you are a married Catholic man in one of the five Eastern Rites you can seek ordination to the Priesthood. There's no guarantee that you will be ordained. If you are a married man in the Western Rite you can seek ordination to the Permanent Diaconite. There's no guarantee that you will be ordained.
Or, if I were a priest, I cannot decide later to be married? I'd have to leave the priesthood
In the Western Rite prior to ordination to the Priesthood you would have agreed that you were called to the discipline of celibacy. If you decided later on that instead of being a Priest you now wanted to get married then you would be laicized and removed from active ministry. Both of those would be choices that you made with free will.
In the Eastern Rites, if you were married prior to ordination you would have to stay married unless your wife died then you would have to adopt the discipline of celibacy. If you were single prior to ordination then you would have to stay single if you wanted to remain a Priest. If you aspired to be a Bishop then you would have to remain celibate. All of those choices would be made with your free will and agreed to prior to ordination. The Orthodox Church has the same policy regarding celibacy and their priests.
That's a forced celibacy that never exists in Scripture of God's Word, and it's therefore unbiblical.
Incorrect. The choice of freely giving up everything, including a wife, in order to serve God is indeed Scriptural and a sacrifice praised and encouraged by both Christ and St. Paul. No one held a gun to the Apostles head to follow Christ and no one holds a gun to the head of a man considering the Priesthood in the Catholic Church to follow Christ. That is a choice made with free will. You have a very poor comprehension of Scripture and the Priesthood in the Catholic Church. Incidentally, I highly doubt that you know anything about the Priesthood of Melchisedech, its mention in Scripture in both the Old and New Testaments, its relation to Jesus Christ or its relation to the Priesthood in the Catholic Church.
I suggest that in the future you actually study Scripture before you attempt to opine on it. The question you should be asking yourself is why, when celibacy is so highly praised in Scripture, that so few, especially those who claim to be "Bible believers" follow the discipline and the example set by Christ, the Apostles, St. Paul, et al.
"For there are eunuchs, who were born so from their mothers womb: and there are eunuchs, who were made so by men: and there are eunuchs, who have made themselves eunuchs for the kingdom of heaven. He that can take, let him take it." Matthew 19:12
"Then Peter answering, said to him: Behold we have left all things, and have followed thee: what therefore shall we have? And Jesus said to them: Amen I say to you, that you who have followed me, in the regeneration, when the Son of man shall sit on the seat of his majesty, you also shall sit on twelve seats judging the twelve tribes of Israel. And every one that hath left house, or brethren, or sisters, or father, or mother, or wife, or children, or lands for my name's sake, shall receive an hundredfold, and shall possess life everlasting. And many that are first, shall be last: and the last shall be first." Matthew 19:27-30
"And Peter began to say unto him: Behold, we have left all things and have followed thee. Jesus answering said: Amen I say to you, there is no man who hath left house or brethren or sisters or father or mother or children or lands, for my sake and for the gospel, Who shall not receive an hundred times as much, now in this time: houses and brethren and sisters and mothers and children and lands, with persecutions: and in the world to come life everlasting. But many that are first shall be last: and the last, first." Mark 10:28-31
"Then Peter said: Behold, we have left all things and have followed thee. Who said to them: Amen, I say to you, there is no man that hath left home or parents or brethren or wife or children, for the kingdom of God's sake, Who shall not receive much more in this present time, and in the world to come life everlasting." Luke 18:28-30
"But I would have you to be without solicitude. He that is without a wife is solicitous for the things that belong to the Lord: how he may please God. But he that is with a wife is solicitous for the things of the world: how he may please his wife. And he is divided. And the unmarried woman and the virgin thinketh on the things of the Lord: that she may be holy both in body and in spirit. But she that is married thinketh on the things of the world: how she may please her husband. And this I speak for your profit, not to cast a snare upon you, but for that which is decent and which may give you power to attend upon the Lord, without impediment." 1 Corinthians 7:32-35
Why do people follow this stuff?
Why do people like you not know what Scripture actually says?
Perhaps you are not aware of many Anglican and Lutheran ministers who were previously married and who have converted to the Catholic faith, brushed up on the Catholic theology and are fully accepted into the priesthood ranks of their dioceses. I think that our diocese has at least two such priests.