It can happen to the biggest companies – today’s big online thing can quickly become tomorrow’s pariah.

Last week AppStats – a Facebook app traffic monitoring tool – announced photo sharing site Instagram has lost nearly half of its 16+ million daily users in one month.

One. Month.

The user stampede follows two major publicity hits for Instagram in December.

The first was Instagram’s decision to stop its users’ photos from being directly viewable on Twitter – part of an ongoing souring of the relationship between the two companies, which has intensified since Facebook acquired Instagram. As is usually the case when services are removed, downgraded or made demonstrably worse, Instagram insisted it was an improvement to get the “best user experience for Instagram users”.

Breaking a feature enjoyed by many people using both Instagram and Twitter was regrettable, but it was nothing compared to the blunder Instagram was about to make.

In mid-December, the company announced it was revising its terms of service. This is not unusual; companies do it all the time. What raised the ire of the internets at large was a change regarding licensing of photos posted to Instagram.

“Instagram does not claim ownership of any content that you post on or through the service. Instead, you hereby grant to Instagram a non-exclusive, fully paid and royalty-free, transferable, sub-licensable, worldwide license to use the content that you post on or through the service.”

So, we don’t own your photos. You’re just going to let us use them as we wish.

Much wailing and gnashing of teeth ensued, celebrities threatened to leave the service, and only a week later Instagram CEO Kevin Systrom publicly backed away from the most contentious changes.

However, the damage may have already been done. Internet users are quick to move on to alternatives if they get even a whiff of something they don’t like in a service (see Digg).

Redesigns and changes can give your site a big boost if they genuinely offer users something they want, but no amount of “we’re doing what’s best for you” will convince users to accept something they don’t like or want.