While ChatGPT took two months to hit the 100 million user mark and video-sharing app TikTok took nine months, Instagram itself took two and a half years to reach that mark after its 2010 launch. Twitter is thought to have around 200 million regular users but it has suffered repeated technical failures since Elon Musk bought the platform last year and sacked thousands of staff.
Musk, who also serves as the boss of Tesla and SpaceX, has also alienated many users by introducing charges for previously free services and allowing banned right-wing accounts back on the platform.
Several rivals have emerged but most are niche platforms without the capacity to grow at the necessary scale to dethrone Twitter.
