Well, here is why:
The Feast of Sukkot is the last of the annual celebrations. This is the supreme feast of remembrance of what YHWH did for the Hebrew people and they are commanded to "Dwell in booths for seven days" (Leviticus 23:42), and it is an odd transition from one of the most solemn days of the year (Yom Kippur) to one of the most joyous.
Deuteronomy 16:13-15 states: "You are to keep the festival of Sukkot for seven days after you have gathered the produce of your threshing-floor and winepress. Rejoice at your festival - you, your sons and daughters, your male and female slaves, the L'vi'im, and the foreigners, orphans and widows living among you. Seven days you are to keep the festival for Adonai your God in the place Adonai your God will choose, because Adonai your God will bless you in all your crops and in all your work, so you are to be full of joy!"
To dwell in booths means you abandon all your usual conveniences. You encumber yourself to experience a tiny bit of how the Hebrews, fleeing Egypt lived as they traveled for 40 years. Yet, we are asked to enjoy in this time and celebrate this "end of the feast season".
Enter Ecclesiastes 3
This chapter seems to be the ideal reading for Sukkot! We are commanded to celebrate this season, at this time, and verse 1 begins: "For everything there is a season, a right time for every intention under heaven." A lengthy list of other "times" follows verse 1, with the conclusion (verse 11) that "He has made everything suited to its time; also, he has given human beings an awareness of eternity; but in such a way that they can't fully comprehend, from beginning to end, the things God does."
Ecclesiastes then "lets loose" (verses 12-14): "I know that there is nothing better for them to do than to be happy and enjoy themselves as long as they live.
Still, the fact that everyone can eat and drink and enjoy the good that results from all his work, is a gift of God. I know that whatever God does will last forever; there is nothing to add or subtract from it; and God has done it so that people will fear him."
What a wonderful way to describe what YHWH asks of us at Sukkot than to "let go", enjoy what He has given us, and to look forward to the coming year of His provision for us! (Remember, Sukkot, by its very timing in the year, is the end of the agricultural season, so what better time than Sukkot to ponder His provision in our lives - even today, even though most of us don't know or live by the agricultural cycle - we can still be joyous and thankful for His provisions in our lives!)
Our personal struggles...
Chapter 3 concludes with what at first sounds like a let-down. Verses 16-21: "Another thing I observed under the sun: There, in the same place as justice, was wickedness; there, in the same place as righteousness, was wickedness..." What are we to make of this?
Well, we find the answer in verse 22: "So I concluded that there is nothing better for a person to do than take joy in his activities, that that is his allotted portion; for who can enable him to see what will happen after him? " So take joy in Sukkot, to appreciate your allotted portion, and trust in YHWH in whatever He has in store for you as one of His chosen!