does every one need an interior designer?

It really depends I guess. I know people from my own friend circle, who aren't professional interior designers, but have done an amazing job in redesigning their homes.

It all boils down to your priorities that you have at the moment. If you feel that you have a vision as to what your home ought to look like, and you have the time and resources to get in the market and find the necessary stuff, I'd suggest you to go ahead and get it done. It is very satisfying to model your own home based on your vision. Because it is all yours, all of it, not to forget that this would earn you major bragging rights and respect.

Then again with the number of modern materials and space saving furniture and even space saving stairs (I mean who even thought of that???), a professional view would help you gain a fresher perspective and a different angle to your vision. Also, you may gain insights on how to use your financial resources more efficiently, and stay within your budget, and still get the look for your home that you always wanted.

To summarize, hiring an interior designer is a very personal choice. If you choose to hire a designer, I recommended to first get acquainted with the designers style, maybe even a recommendation from a friend would be very helpful. If not, I would suggest that you go through magazines like Good Housekeeping to get ideas to remodeling your home.

Hope this helps!! Cheers!