Concerning the premine, here's a quick calc:

- July 2018: expected supply: roughly 20.000.000 coins, share of premine = 600.000 / 20.000.000 : around 3% (!!!)
- July 2020: expected supply: roughly 38.000.000 coins, share of premine = 7.200.000 / 38.000.000 : around 18.5%

If you consider that some coins are financing themselsves on a regular basis, devs share could be as high for some specific coins. Ether had a 17% premine back in 2015, still it is a successful coin, with a high market cap, and devs (which is not limited to Vitalik) could build a real trust around their project. At that time, there were also fudders, stating miners/buyers would be scam victims. Where's ETH now?

As I can understand fears - especially when it comes to "modern core values" of monetization -, I think overstretching potential issues isn't the way to go. You don't trust? Fair enough. Just buy 10 SUM and leave them in a wallet for 2-3 years and see by yourself. It falls? You'll have lost 50 bucks at most. It succeeds? You'll have more money. On my side of things, I could repay my mining equipment, so now, it's only "bonus" time, and I trust this project enough to have a reasonable quantity of  SUMOs in stock.