Having noted recently for myself that quite a few of my brothers and sisters in Christ have small regard for prophecy, I went looking for a good article on the matter. This one is very good and covers most of the points that need to be considered. The two main points I think most important are that it validates God’s Word and that it also validates the deity of the Messiah. The Messiah’s life also validates prophecy, as well, the Lord having fulfilled so many with His life and sacrificial death.
“I am God, and there is no other; I am God, and there is no one like Me, declaring the end from the beginning and from ancient times things which have not been done. . . I have spoken; truly I will bring it to pass. I have planned it, surely I will do it.” (Isaiah 46:9-11)
I don’t know how it can be said that prophecy is about gloom and doom. It excites and thrills me to see prophecy fulfilled.
Check the scriptures with a heart open to the Holy Spirit’s teaching. You may be amazed at what He will reveal to you.