Why would I want to choose Fiber over a faster cable connection?

[wireless]

Hello,
I currently have an existing Internet 15 connection with Telus. I'm supposed to get fibre installed around November and I'm just wondering why I would want to choose Fiber over this offer I just received from a competing ISP. Right now I pay $55 a month for 15 Mbp/s down and this offer will give me 500 Mbp/s down for $79/month for two years. When fiber is installed, will my internet speed dramatically increase at no extra cost? Cause how does that work y'know? Once the line is changed to pure fiber I'm still at that Internet 15 plan so do I get upgraded to like Internet 75 or am I still capped at 15 Mbp/s down once the pure fiber is installed? Cause then I don't really see the point or how it would benefit me since apparently pure fiber increases the maximum download and upload speed but I don't really need a high upload speed or very low latency. My use case is just downloading 100 GB games and watching stuff at 1080p and so I'm wondering - for my use case - should I take this deal? If not, why should I continue to stay with Telus? I understand I'm going to get some biased answers since I'm posting on a Telus forums so I hope I could get some factual information to help me make a decision.

Thanks!


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