Say you have 2-step authentications with strong and different passwords and a different email for each account and say your following goes from 1k to 500k people for example in a short period of time. Do you just roll on as before in respect to your accounts' security or do you employ changes? If the latter, what should those be?
Standard security risk assessment model would give a tentative yes to increasing security. standard model evaluates risk as the likelihood of an incident and the cost of the incident balanced the cost of reducing the likelihood or cost of the incidence.
An increase in exposure, as measured by an increase in followers, would indicate and increased likelihood of an incident (more people know you exist, and a greater value of your account to those who would steal it -- increased quantity and quality of potential attackers). Presumably an increase from 1 to 500K followers would indicate greater revenue as well, so the cost of an incident (interruption of revenue, lost goodwill etc.) would increase as well
So you would want to balance that out as long as that was doable in a way that doesn't cost more than you're making. What options are available will depend on the platform(s) you're using and the level of control you have.