Can effective altruism (specifically Earning to Give) and Buddhism co-exist if Earning to Give was done to the extreme? (This may be more of a philosophy stack exchange question; feel free to move it. Actually, the example I give below is probably off topic or something since it's the real meat and potatoes of the question: money.)
In general, where does Buddhism and the philosophy of effective altruism split, when one spends all their time Earning to Give? (Again this question assumes many things, a chat would greatly be appreciated.)

While reading The Middle Way by the Dalai Lama (give as a gift) this question keeps surfacing. In the book is says, "the aspiration to bring about others' welfare and the aspirations to seek buddhahood for this purpose." Maybe I'm misdefining the translation of "welfare"...but this point will come up again and again when reading about Dharma anyway. Please help answer the essential question, and not the details of this specific quote. It is arbitrary for the main game.

Perhaps what I mean is better though an example:
Somehow assume that a person has this extraordinary altruistic resolve, or even bodhicitta (if that's close to correct). And they decide to spend much time Earning to Give. Let's assume they work 16 hour days (from one job being professional, such as an electrical engineer, and a second in a similar job or a factory job--six days a week). Try to also assume they get enough sleep (7.5 hours), stay hygienic (taking a shower during a break at the factory), manage to eat bagged lunch, and everything else to spend virtually no money on unnecessary expenses such as rent (by sleeping in a van near both companies). And so, after all that, there is no time to meditate. Literally, every waking hour is spent Earning to Give. How on earth can this person seek buddhahood?! And wouldn't others' welfare be all what this person lives for anyway? (Additionally, since this question is seeped in money, also assume that 'Robin Hood tactics' are not a means to Earning to Give...)
The question is asking about Bodhicitta (Mahāyāna Buddhism), Confirmed Candidate of Future Buddha (Theravada). 
I would like to explain Striving to attain the Nirvana with an example flying with airplane. If you offered more money, you can get more luxurious class or seat. 


  so, after all that, there is no time to meditate.


There is most simple way to attain Nirvana. Concisely, meditate and then attain Nirvana. This is a kind of flying with an economy seat. Because you offer less, you just get a seat what you pay for. 

Here is Sutta Bahiya Sutta. He was the one who attained Nirvana the most fastest way in Gautama Buddha's teaching. Even though he attained Nirvana in fastest way in his last life meeting with Buddha, he strived for many uncountable years during his past lives. It means that it is not an easy job to be a student with flying colors in Buddha's teaching. 

For the life of a confirmed Candidate of Future Buddha, the job is extremely harder to accomplish; only the strongest determination and dedication can go through because being a Sammasambuddha is highest class of attaining Nirvana. If you are going that way, you have to strive for perfect in offering. "Earning to give" or Earning to offer" is the very first step to strive for being Sammasambuddha. The candidate offered even his life to complete his offering capacity. There are countless of lives where candidate of Gautama Buddha dedicated just offering (Earning to give/donate). Yes, "there is no time to meditate", there might be the case because he just strived for donation, trying not to attach anything he owned. But the act of Dana is very first cornerstone to become a Sammasambuddha. 

Here is list of paramis


  And wouldn't others' welfare be all what this person lives for anyway?


I do not know exactly to what extent he lived/survived only for other's welfare (at least he needed to consume to be alive in particular past life but probably, I guess). I like to request reference/citation if anyone knows about Buddha past lives regarding to this statement.  


  How on earth can this person seek buddhahood?


This person had long way to complete all the paramis to become Buddha. Not a single life, not 100 lives, not 1000,000 lives but uncountable lives he strived for being Buddha. 


  where does Buddhism and the philosophy of effective altruism split, when one spends all their time Earning to Give?


Yes, it was done to extreme by the example above. Yes, both can co-exist if you're moderate person and you are going to strive for attaining Nirvana in normal way (just want to be a normal student of Buddha's teaching). 

For example in real life two students may differ in determination and dedication. One is striving for LSAT to attend Columbia Law School or Harvard Law School. Another might say "he is not himself recently" but two students differ in their goals. So that kind of case is expected.