10% is the charitable giving limit.

Not in the U.S. (note these are in pre-tax earnings, so they translate into less in foregone consumption than they do in donations made).

There are limits to how much you can deduct, but they're very high.

For most people, the limits on charitable contributions don't apply. Only if you contribute more than 20% of your adjusted gross income to charity is it necessary to be concerned about donation limits. If the contribution is made to a public charity, the deduction is limited to 50% of your contribution base. For example, if you have an adjusted gross income of $100,000, your deduction limit for that year is $50,000.

Regarding this:

If I worked on Wall Street anywhere but Vanguard I would be bilking people out of their life savings, and at Vanguard I wouldn't be making $100 K a year. Someone working as a tobacco farmer to raise money for cancer research has some misplaced priorities.

See this essay:

Goldman has 32,000 employees. An upper bound for the harm caused by the marginal employee is thus the total harm caused divided by 32,000. For the harm to outweigh the good, Goldman would therefore have to be killing at least 3.2 million young people each year, or doing something else that is similarly harmful. That would mean that Goldman Sachs would need to be responsible for around 5% of all deaths in the world. Bear in mind that Goldman Sachs only makes up 22% of American investment banking, and 3% of the American financial industry - if the rest of finance is similarly bad, then it would imply that finance is doing something as bad as causing all the deaths in the world..

Let’s consider the American financial industry in general. Upcoming Giving What We Can research estimates that it would take $200 billion a year to move everyone in the world above the $1.25 poverty line. That figure will only be $74 billion in 2030. The employees of the financial sector could do this if they transferred (e.g. via GiveDirectly) 30-75% of their salaries to those in extreme global poverty (depending on what date you want to achieve the goal by). In other words, if everyone in finance were Earning to Give, it would be possible to end extreme global poverty within the next twenty years. Harm would only dominate if the financial sector is doing something roughly as bad as single handedly causing all global poverty.