This is great but it's missing one thing: having to apply for funding each year (time consuming!) with the statistical expectation of not receiving it. Then having to TA to help towards making-up the difference (it does not).
Then, spend egregious amounts of time each year filling out expense reports for conferences you attended. Also, take-up more part time work because it takes 4-6 months for the reports to get processed and you need to pay off your credit cards.
Profs apply for research grants that, depending on the grant terms, can be used to pay your stipend. There is no guarantee that your prof can secure that funding or afford to allocate it to support you. As a result, it behooves you to apply to funding agencies to get studentships that fund you.
Another note is that it is also a prestige thing. Getting grants as a graduate student makes you way more competitive when applying for PDF/PhD positions.
Then, spend egregious amounts of time each year filling out expense reports for conferences you attended. Also, take-up more part time work because it takes 4-6 months for the reports to get processed and you need to pay off your credit cards.