Final answer:
The speaker could cite the phrases that emphasize a desire to make a difference and that no qualifications are needed except a desire to help, to argue that voluntourism can cause harm when done by unskilled individuals.
Step-by-step explanation:
The speaker of "Voluntourism: An Opportunity Too Good to be True" could use the line "If you've always wanted to make a difference, here's your chance." and the words "The only qualification necessary is a desire to help" from the advertisement "The Opportunity of a Lifetime" to support their point. These elements suggest that the primary qualifications for voluntourism are a general desire to do good and a passion for travel, rather than specific skills or expertise that would be beneficial in complex situations such as providing aid. This reinforces the critique that voluntourists often lack the necessary skills and proper motivation, which can end up doing more harm than good.