Top 10/40/100 charts.... Why do songs stay in there so long?

Top 10/40/100 charts… Why do songs stay in there so long?

I’ve been revitaliSing the popular stuff in my library, and whilst browsing through the charts, i find it astounding that songs can stay popular and in the charts for so long… It just doesn’t make sense to me why the general public would buy a song that was ‘in’ 6 months ago…
Take this link for example (Australian Aria Charts)

Cinema - Benny Benassi has been in the dance charts for the last 27 weeks! Thats almost 7 months… And i’ve seen some of the RnB stuff stay in there even longer!

WHY!!! This defies any logic i can understand… Why would people purchase a song that was popular half a year ago? All their friends already have it, and it should have moved on as a phase, as it got overplayed by the radios and at parties etc… But No? It continues to be bought, thus stays in the charts, thus remains ‘popular’, thus continues to get radio plays, thus gets even more over played. I just Don’t understand!

Opinions?

Edit: Even Adele has managed to stay in there for 35 weeks!

Maybe it is because as a song rises in the charts it is exposed to people that never heard it six months ago. While I have an ear to the ground and know the unreleased tracks in my favorite genre, often six months previous to the release, most people don’t follow DnB that closely. I often feel that dance music suffers because of the cool kids club playing tracks to death before the release. On the other hand it probably makes for stronger initial sales, which leads to the track being exposed to an even wider audience, keeping it in the charts longer.
Really though I think I’ve bought on track from the top of the charts in the past year, and one compilation. I’ve also passed on tons played out prerelease unless I thought it would really stand up to time.

Top 10/40/100 charts… Why do songs stay in there so long?

Because people are naturally averse to change. People eventually will get sick of the same song but it takes a while to trickle down.

People don’t know what they like; they like what they know.

You know how Get Low and Yeah! still get played in top40 clubs?

It’s no different. Be happy songs last a year instead of 5 if you like new music.