Take an economics class....
Just 10,000 copies sold bring in less than $150,000 after you take into effect marketing, packaging and production.
Now you have 10,000 customers you have to provide a lifetime of support. You can't do that alone, you have to hire trained personnel to tackle that task. How are you going to pay them? $150,000 won't last 1 year....
hmm:
marketing - word of mouth. cheap and most effective
packaging - download of the net. cheap and most effective.
production - hmm, if you download, not much production costs...
10k copies @ $20 != $150k
its $200k. simple arithmetic class could have taught ya that.
edit - d'oh - didnt see "after taking into account marketing..."
edit - still, i would estimate a yearly cost of owning a server farm and such to allow others to download to be about ~15k a year. that would be about it. that is easily manageable with an electrical engineering degree, no?
also, it would be a software product. most software products dont generate too much profits, unless you obtain most of the market share. i also have a few hardware ideas up my sleeve as well, that, if they were to be brought to retail sale... well, heh, i would not have too many financial problems. trust me on that one.