Yes, exactly a sales tactic. Not just 10%, they will be able to pay even 100% because they will not be paying in BTC (nor in any reputed altcoins) but in their new token.

You invest BTC (or ETH or fiat or any altcoin) to buy some new tokens and they will get you 10% of your holding everyday but value of the token will decrease consistently and at some point it will value less than 1 satoshi and then no one will be ready to buy those tokens.

Look at this trading pair : https://yobit.net/en/trade/EGOLD/BTC
6778 BTC worth of tokens are listed for selling at the price of 1 satoshi and there is no buyer.

For example, people would have bought that EGOLD for the price of 100 satoshi and their holding might have grown 1000 times still they are not able to sell, will you call this a ponzi or a legit business model?