Indeed, competition would have such a high burden... they might have to ssh into a server and enter some cryptic command like "dnf install ejabberd" and hire a sysadmin for at least 4 hours to set it up. They would also have to create a website.
A more pressing problem is that you might be targeting people unwilling to pay anything, and they might be willing to consume whatever level of services you are capable of providing.
And you kids should be advised of the existence of email, email lists, and online communities using HTTP-based services. It may be that there are a whole bunch of options in active use, some of which are transmitted entirely across open channels and that have no proprietary components.
It may be that the primary distinguishing characteristic of twitter and facebook, the reason they are so popular, is that they are proprietary and therefore somehow elite! Officialish-looking. Be less credulous.