There's a half truth in what you were told. An empty channel does have a cold start problem, nobody joins something that looks abandoned, so a little social proof helps. But fake subscribers, even human ones, are a weak base, and here's why.
Telegram and your ad results both care about view rate, not headcount. A channel with 5000 padded subs and 80 views per post reads as dead, your post view to subscriber ratio tanks, and that hurts both Telegram's own discovery and the cost per result on your ads. You also lose your real signal, you can't tell if your content converts when the audience is filler.
For a sports analysis channel the strongest move is content first. Post genuinely sharp free analysis and a few called results for a couple of weeks so there's a reason to subscribe, then point ads at that. If you want a seed so it doesn't look empty, keep it small and use real active members, not a bulk bot dump. Then let retargeting and word of mouth compound.
Short version, social proof yes, a fake pile no. The lever is engagement, not a big number that just sits there.
Best,
Floqal