At large enough size, commission/trading costs are not necessarily a significant factor--individuals are just not great at stock picking and timing the market.
Let's say I sell you an option to buy (from me) a share of TWTR at $100 at any time through the end of January. I have just sold you a call option.
If I already own a share of TWTR that is not tied up in another contract, the call is considered covered (meaning I would not have to go out and find a share to buy if you exercised the option).
It is not denominated in USD. It's a currency, and like any other currency you can exchange it for others, including USD, which is why you often see exchange spot prices in USD.
It's not about the cost of college, at least here. Places like Stanford and Princeton have generous enough financial aid programs that if you can't pay for it, they will (presuming you're accepted).
Sacrifice by definition must be voluntary, otherwise it's just servitude, so saying he volunteered is not a good argument against calling his service sacrifice.
Likewise breaking the law is not necessarily wrong, and what's legal and what's moral don't always overlap. Consider slavery.
As for the last part, it could be a duty to leak code if your startup is doing something highly immoral. No one's arguing for what you said; it seems like trolling.
I actually started wearing a watch regularly a couple of years ago after thinking a cellphone was enough for a long time.
There are a couple of advantages: it looks good (maybe the only male fashion accessory acceptable in a conservative professional environment besides a wedding band), and also it much easier to glance at and allows me to not check my phone throughout the day--especially helpful in conversations and meetings where it'd be rude to pull out your phone.
It's not really his idea, but it's probably a good one. I remembered it as being called a Tobin tax, but that really only applies to currency exchange. Instead, it's just a securities transaction tax: http://en.wikipedia.org/wiki/Financial_transaction_tax#Secur... .
Yes, they basically don't say what they're going to spend the money on.
But it may have been (they hint at this) that they didn't need or want the funding so much as to have AH invested in the company. Taking their investment may create something of a partnership and gives them access to AH's advice/rolodex and encourages future support. It also gives them a concrete valuation to cite down the road.
The NPV is how much a thing is worth/costs now after taking that into account and discounting future cashflows appropriately.