At their peak it was like 33% or thereabouts. The claim that they were "abandoned" suggests, well, that the browser was abandoned when it wasn't. It's a mischaracterization. Market share is about some combination of (1) software quality, (2) visibility and (3) distribution lock in. Chrome managed to be arguably better on (1) but it's due to (2) and (3) that it became dominant.

If (1) was all that mattered we would all be using the Preso engine version of Opera right now.