In todays market? yes. Especially for a EPL club like Spurs who are very well equipped financially. For Sporting for example its an enormous risk but for you guys not so much. 30M is pennies in todays market.
As you said, maybe he turns into Daka.
Or
He goes to one of Ajax, Sporting, Benfica, Dortmund, Brighton does insanely well and now if you want him your going to have to pay 100M. Just look at what Evan Ferguson would cost if you wanted to get him for Brighton. He has shown nothing to be worth a high valuation yet but I have no doubt he would cost 100M.
I can't predict if he will be great or not, but for 30M I believe its Worth a punt. The potential is clearly there. He has finishing ability that you don't teach especially in someone so young.
Goncalo Ramos just went for 80M to PSG and I believe Orban would score more goals than Ramos did if he played for Benfica.