By using it. Sure, it is a "free" app, but usage is profit when the cost is zero. It's not immoral profit, but it is profit nonetheless.
Not sure I follow you here. Since I only use it for my personal enjoyment, I don't guess I see where the profit comes in.
I don't agree with Chad here, but I follow the logic -
You are using MAME for Free and the roms for free. If you had to code MAME yourself (or hire a programmer to do it) and license the ROMS, it could cost you years of time and thousand of dollars, so (according to Chad), that is your profit.
Examples of why this doesn't hold up:
I primarily use Gimp (
www.gimp.org) freeware for photo editing. It is very similar to PhotoShop, which would cost me about $650, last I heard. According to me, I would be ripped off about $650 (well at least $500, Photoshop does probably have $150 value in added features over GIMP) if I used Photoshop. According to Chad, I profited $650 by not buying Photoshop. Depends how you look at it.
Let's say I'm a Linux user. I install Linux on all 100 PC's at my office. To do this with WinXP Pro (at I think $200 a copy), would cost me $20,000. According to Chad I made a profit of $20,000. According to me, I avoided an expenditure of $20,000. Lucky for us, Chad doesn't work for the IRS.
Similar logic most of us can relate to. Mrs. BYOAC member goes to the mall and spends 100 dollars on clothes that she really doesn't need at 75% off. In her eyes, she SAVED $300. In our eyes, we're out $100.
Final hypothetical example - I cut my neighbor's grass last week, without asking for payment, and he fills up my 2 gallon gas can, without asking for payment.
Did I break even, since my labor for mowing the yard was approximately equal to the $6 cost of the gasoline.
Did I profit by $6, since other than time and mower wear and tear, the mowing didn't cost me anything, but the gas would have cost that - plus my time and gas to go get it.
Did I profit by $10 billion dollars - as that is what it might cost me to buy the land rights, set up the drilling rig, pump the crude out of the ground, build a refinery and hire people to refine and test the 2 gallons of gasoline for me.
It all depends on how you look at it.