I agree it is better to have a bigger roaster and for the majority of people something like a 5kg+ roaster will be a great investment and makes starting easier if you can afford one, also a lot of 1kg roasters are not suitable as production roasters (aillio bullet for example)
1kg is really hard to make a lot of money with but I know several people who did it for a couple of years and now have bigger machines, they were profitable but as you say it will be hard especially if you don’t have other revenue streams like a small roastery/cafe or work events with some sort of mobile coffee setup
With the costs of everything from electric to rent to coffee prices increasing quite dramatically it is a very tough time to get into coffee roasting and the competition is very strong. It requires a huge amount of time and investment and profitability during early growth will be very low.