You can build a $30k MRR business with 1% the effort you need to build a $30M MRR business. Once you escape a certain size/scale the day to day operations grow in scope. So do you want to deal with HR or payroll? Do you want to have to keep bringing in $100k worth of google ads traffic a month?

The question to think about is can the small idea potentially be big? Or is it a TAM limited scope? Don't forget there is horizontal vs vertical scaling to think about too.