We have increased the member limit for supergroups to 100,000.

If you're looking to get more users in your community, the best strategy is to open a channel on Telegram. Channels are the perfect tool for broadcasting your messages to the masses because they can have an unlimited number of subscribers.

With channels, you can broadcast important announcements to millions of people or post answers to the most popular questions from members of your supergroups.

See this post for more info on channels:
https://telegram.org/tour/channels