NCSA was before them, and Netscape (and later Mozilla after server business didnt materialize) basically clean-room copied NCSA from scratch. Pioneers in new directions can define space but still get slaughtered because the next entrant (Chrome) doesn't have product inertia and has/should learned lessons of what didn't work.
Some of it maybe popularity/marketing of not having a huge org behind them, but odd rough-edges did more to sabotage stickiness. Plus, competing with deep pockets giving away something for free is an unnecessary competitive war of attrition, especially by not differentiating: most secure browser or best browser for X/Y/Z.
TBH, Opera was a much better browser than either Firefox or Chrome until version 11 or so.
Unfortunately, technical prowess is not enough to gain traction. Being closed-source and costing money (until version 8) was a much bigger factor for their failure.
Still, back then there was simply nothing that was as fast or usable as Opera. Rest in Peace.
Some of it maybe popularity/marketing of not having a huge org behind them, but odd rough-edges did more to sabotage stickiness. Plus, competing with deep pockets giving away something for free is an unnecessary competitive war of attrition, especially by not differentiating: most secure browser or best browser for X/Y/Z.