Because His word says we should(and it is respect but also more, if you fear God then you wont go against Him or His ways and Word), and not just extensively in proverbs but also Revelations ch 15 for example. it is not to be confused with the fear of man, or fear in general, as these things crush and quench true love, and His Word says His True love casts out all fear amongst other things(1 John 4v 18).
You need to read His Word regularly in communion with Him(YHVH/YAHshua/Jesus/Holy spirit/Father)so others cant deceive you or confuse you, He promises if You do the Holy Spirit will lead you into all Truth. Seek Him earnestly and you will find Him, amen