Are you looking at tradition as the things you might do every Christmas or Easter?
That’s not the tradition we are talking about here.
How did Paul know that Jesus had appeared to 500 people after his Resurrection? It is not in any Gospel.
There is also a quote of Paul’s quoting Jesus, “It is more blessed to give than to receive.”
But you will not find that in any Gospel either.
Holy Tradition is inspired by the Holy Spirit for one individual to speak the truth to another individual. How else did Paul find out about these things?
Do you have any Holy Traditions you would like to share with us?
However if you would like to talk more about traditions, we can.
How did Paul know that Jesus had appeared to 500 people after his Resurrection?
He likely heard about it from the apostles, whom he often dialoged with. As a devout follower of messiah, he would have no doubt asked them often about their experiences with him.
There is also a quote of Paul’s quoting Jesus, “It is more blessed to give than to receive.” But you will not find that in any Gospel either.
Not that direct quote perhaps, but it is likely that he either learned of that quote while discussing with the disciples or perhaps he was summarizing Jesus's point in this parable:
"Then Jesus said to his host, “When you give a luncheon or dinner, do not invite your friends, your brothers or sisters, your relatives, or your rich neighbors; if you do, they may invite you back and so you will be repaid. 13 But when you give a banquet, invite the poor, the crippled, the lame, the blind, 14 and you will be blessed. Although they cannot repay you, you will be repaid at the resurrection of the righteous.”(Luke 14)
That fact that this particular quote was not listed in the Gospels is not altogether surprising. Summarizing His whole life and teaching would have been a very difficult thing. After all, John tells us that "Jesus did many other things as well. If every one of them were written down, I suppose that even the whole world would not have room for the books that would be written."(John 21) To learn further information about Jesus, one would have had to talk to his apostles and other close followers, as such a devout disciple as Paul surely did.
I do agree with you that the Holy Spirit can inspire people, and has often done so. However, all such inspiration or revelation or tradition must be tested against God's Word. If it goes contrary to God's word, then it is not inspired of God. As Malachi 3:6 says "I am the Lord, I do not change." And 1 John 4:1 instructs us "do not believe every spirit, but test the spirits to see whether they are from God, because many false prophets have gone out into the world."
You also mentioned Christmas and Easter. Those are some very good examples of traditions that have not been tested against God's word, and that in fact go contrary to it. Those holidays have numerous roots on paganism, which you can read about further if you would like. These are just a couple suggested sites. You can do your own research too.
http://www.eliyah.com/paganexp.html
http://www.goodnewsaboutgod.com/studies/holidays2.htm
Some people will say, "well maybe these things did have roots in paganism, but its not about that for us...we're doing it to worship God now." The problem with this is that God does not want to be worshiped using pagan traditions. He says so:
"be careful not to be ensnared by inquiring about their gods, saying, “How do these nations serve their gods? We will do the same.” 31 You must not worship the Lord your God in their way, because in worshiping their gods, they do all kinds of detestable things the Lord hates." (Deuteronomy 12)