May be you stopped working or stopped buying ads. Traffic is all about doing something or getting it done for you. I read an interview granted a past CEO of coca cola and learned a lot. They asked him, 'Coca cola has become a household brand all over the world that one'd think they no longer need to advertise. But, surprisingly, Coca cola is still in the front line in advertising' (not the exact words). And he asked them 'if an electric train is on the fast track and suddenly electricity is turned off, what'd happen?' If global names like Coca cola keeps the tempo going, then everyone should. No respite at all. Be happy.
Maybe you lose some nice beneficial ways to get traffic, like ad, social community or SERP. Or your site is locked into sandbox for some illegal SEO skills.
Give us some more details......how big is the lost in traffic, have you done any changes lately, have you tried something new, you did not post anything for some time.....more details.
Is it just traffic or rankings too? I can see two reasons for this... 1. Google has slapped some sort of penalty to your website. 2. When you were checking your ranking (when your website was ranking on the top) you were getting personalized results. One Advise, Do check for Google Analytics report.... Pin point the keywords and the pages for which your traffic has dropped.
Losing traffic can be due to a number of factors and to say something specific with what you have given is very difficult to determine. Google Sandbox, Dance, penalty, spammy links are all factors that make sites and visitors disappear from a site.
This is so true! Alot of time when we are on top we stop fighting. Being numer 1 is an ongoing process.