My understanding is that DDG relies on selling "keyword match" type ads based on what you searched for.
For example: if you search for "standing desk", it will include one or more paid ads that are keyed for some combination that matches with the search query. Those ads aren't targeted at you based on your gender, or your home address or where you eat lunch on Tuesdays or how many devices you regularly use or any number of other creepy shit Google tracks about it's flock of willing cattle.
How then duckduck go managing to compete with them wituhout collecting data and tracking user to the same extend? https://fourweekmba.com/duckduckgo-business-model/