I don't really see it as a waste. It is better to remain second every season than to get worse. Arsenal maintaining second position means they are close to getting the title of the Premier League. It is not easy to come out as second best every season; there are teams that are even struggling to be in the position of Arsenal, but they cannot. Having a second position every season in a league like the Premier League is not easy; it proves consistency. The reason why Arsenal is unable to win the league title is just a little problem they haven't been able to solve. Arsenal has a problem with a good striker, and they have always had problems with injuries to key players.
It is not satisfying to be in second place again and again. If you plan to be in second place again and again, when will you win the title? You don't have to do well every season, win one season and try to keep the title. You may not do very well the season after winning the title, because the opponents will find your mistakes and attack you. Then you will correct the mistakes and become twice as strong again. You may not improve much by being in second place again and again. Because the opponents will not spend much time with you and will not be interested in improving in you. They will succeed in winning the title when they find a good striker.