Often, authors feel insecurity. You'll doubt, and second-guess, and wonder...and you'll worry. And I know it's tempting to share ideas, plot points, even whole chapters with close confidants. But you shouldn't. If you're writing a manuscript, wait to share it. Finish it first.
Other People's Opinions
Even authors are only human, and you're going to be influenced by other people. In fact, as an author you should be. Reviews are most beneficial not to readers but to authors. They provide honest feedback, and that's what every author needs.
That's why it seems like such a good idea to solicit advice from those closest to you. But if you start getting that advice before the book is done, it's could change the course of your story. You could be influenced by others, and then it's not wholly your story anymore.
I'm not saying you should give up your beta readers. But you should finish the manuscript before you hand it over. Make sure that if you're going to receive criticism, you're getting it for something that's totally yours.
Finish, yes, but be open to that feedback you receive. Bets readers are a good idea, and sometimes you will need to make changes. Sometimes, you do need to be influenced. Just wait until your early readers can get the whole picture first.