Oil dependent economies around the world have seen revenues fall in the last few years. Alberta is certainly in troubled times and it is hell for those who lost high paying jobs. But the biggest part of the price drop in oil occurred because of market fundamentals that are not set in Canada. The US is now the largest producer of oil in the world. High prices and new technology attracted investment and increased production in more profitable oil producing regions than the tar sands. I don't know why people expected the unsustainable rapid growth in oil production in Alberta to last for decades? Experience should have shown that high price periods don't last forever.
Even Saudia Arabia is planning to diversify its economy away from oil:
https://www.theguardian.com/world/2016/apr/25/saudi-arabia-approves-ambitious-plan-to-move-economy-beyond-oil
Saudi Arabia approves ambitious plan to move economy beyond oil
15-year plan includes diversification, privatisation of state assets, tax increases and creating a $2tn sovereign wealth fund
https://www.forbes.com/sites/ellenrwald/2018/07/25/signs-point-to-trouble-ahead-for-saudi-economy/#7f80553a635d
Even Saudia Arabia is planning to diversify its economy away from oil:
https://www.theguardian.com/world/2016/apr/25/saudi-arabia-approves-ambitious-plan-to-move-economy-beyond-oil
Saudi Arabia approves ambitious plan to move economy beyond oil
15-year plan includes diversification, privatisation of state assets, tax increases and creating a $2tn sovereign wealth fund
https://www.forbes.com/sites/ellenrwald/2018/07/25/signs-point-to-trouble-ahead-for-saudi-economy/#7f80553a635d
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