Well of course this isn't true. We apparently wear regularly only 20% of our wardrobe whilst the rest sits idle and wasted.
Conned by clever marketers into believing the consumerist myth that dictates the constant need to update, outdo and compete we dutifully obey spending more and more cash on stuff we just don't need. The knock on effects of this avid consumerist cycle on the environment are becoming ever clearer...search GREAT PACIFIC GARBAGE PATCH or PLANNED OBSOLESCENCE for example.
Combine the above with a general sense of wardrobe boredom, fit issues and the less often acknowledged, 'I don't know how to wear it', and you can easily account for the other 80%.
Buy less and only what you need
Do some research and innovate
Make it yourself
Pay someone to make alterations
Give it away
Recycle
Upcycle
Buy second hand
Make do
Fix it
Here's my final and somewhat vapid tip the for day...
I recently released a pattern for a halter top. As you can see from the previous post it's somewhat conservative from the front but scoops down to reveal your entire back. Now whilst I don't encounter any errr...gravitational issues I acknowledge this may not be the case for others. So if you're thinking of making one but have hesitated for this reason may I suggest signing up your bikini top for double duty. The strap will show but unlike a bra it will add rather than subtract from the overall look especially in a contrast pattern.