yes, it depends on the context and where it is used in. 욕 from 욕심 means desire or eagerness to something. 욕망, 욕구, 탐욕, like these. and then 심 came from mind, think or heart, for example, 진심, 본심.
so, if 욕심 is used in the context that describes selfish, self-centered, take too much from the limited resource, it can mean greedy.
ex)쿠폰을 공평하게 1장씩 나눠 갖기로 했는데, 그 사람은 너무 욕심이 과한 나머지 혼자 2장을 챙겨갔다.
but if it is used to show your goal, vision or hard-working attitude, it doesn't include negative meaning.
ex)그 사람은 승진에 대한 욕심이 많다.
thus, 저 욕심 많아요 - can be understood in both ways and we need more background or context to figure out what the exact meaning is. he/she is selfish and admit his/her characteristic or he/she is ambitious for business, career, or getting promotion.
and if you want to say that person is ambitious, you can say 그 사람은 야망찬 사람이에요. but if you want to use 욕심 to express it, you might say, 그 사람은 일 욕심이 많은 사람이에요. so you add extra information that the person is ambitious about his/her own work or something like that, and not selfish.
hope this could be helpful!