Wtf kind of math is that? You are saying he needs to buy 600 computers to run 600 bots, when instead you should of skipped half your equation and seen he would need 100 computers for $6,000 to run 600 bots.
Also factor in that the cost of your computer includes a mouse, keyboard, and monitor.
With an efficient botting setup, you are not going to use that for every computer. You will have a dedicated monitor/keyboard/mouse on a switch so it serves its purpose on multiple towers.
Now let's do some math. Even if his 600 bots were making, say, 100k per hour each, that is 60M or about $30 per hour. Since you can (pretty much) run them continuously, that is 1.44B per 24 hours, or about $770 per 24 hours.
With the initial investment of $6000, and a gross profit of $770 per 24 hours, it would take approximately 7.8 days to earn back the money spent on botting rigs.
Now, even if you were to factor in electricity and membership costs (if your accounts were P2P), you would be making a substantial profit each month.
If you were to run your bots 24/7 for a whole month, and I am being EXTREMELY generous by only counting a month as 26 days to supplement script downtime and other difficulties, you are making a gross profit of $20020 in those 26 days.
If you subtract the $6000, you are left with $14020 gross profit to pay off any other expenses plus pocket what you have left over.
BUT, the very next month you are doing this, that computer expense is non existant because it has been fully paid off and you have an extra $6000 in profit or funds to expand.
Now, even if you had labour costs to watch bots/set them up again after RS updates/etc, it isn't going to be a major dent in your profits (and, I should add, it would obviously lead to higher profits than stated above due to me including 4+ days of downtime in the gross profit figure).
In conclusion, BADA BING.
Your math is wrong as well, and the figures you're coming up with are incredibly generous.
1,000 P2P bots @ $4/Membership = $4,000
a $30 VPS will let you run 4 bots, so you'll need 250 monthly subscriptions to a VPS to be able to run them all:
250 x $30 = $7,500
So that's $11,500 for that alone.
Auth codes to fund for 1,000 bots:
1,000 x $14.95 = $14,950
So there's $26,450 for start-up alone.
Each month you're paying $11,500, so for 1 year, you'll be paying the following:
$14,950 + 12($11,500) = $152,950
Now let's calculate time; something money can't buy:
Each bot on average, takes about 1 minute to start up, and generally bots run for an average of 36 hours before getting caught in a random/running out of supplies
1,000 Bots x 1 Minute = 1,000 Minutes = 17 Hours just to start up all 1,000 Bots
Harvesting/Restocking the bots take even longer, I'd say an average of about 3 minutes per bot
So every bot harvest session you do will take the following amount of time:
1,000 Bots x 3 minutes = 3,000 Minutes = 50 Hours to harvest all 1,000 Bots.
Let's say you make 100k/hour per bot, you don't have time to start up your own gold shop so you have to sell in bulk for $0.37/M, or $0.037/Hour per bot
1000 Bots x $0.037/Hour = $37/hour
$37/hour = $888/Day = $6,216/Week = $27,010/Month
That's if each bot ran 24/7/365
Factor in System Updates, which usually occur early in the morning, and are usually on a weekly basis; each System update would cost you 17 hours of restarting bots, which is an entire day.
On top of that, many bots get stuck literally hours after start-up, whether it be in a random event, or just the bot glitching. If you're using free bots from RsBuddy, then expect the 17 hour startup to occur literally every single day. Further hurting your rate of return.
Long story short, there's no way a single person could run a bot farm that can capacitate 1,000 bots; it would literally take a team of ~15 people to effectively manage a farm that big.
. Actually, now that I think about it, that's not a bad idea 
